flu

The Next Pandemic Is Here

Who ya gonna call?  --“Ghostbusters”

We seem to have mostly weathered two-plus years of a pandemic like the world has not seen in our lifetimes. It raced across the globe killing and maiming people, and overwhelming health care capabilities. Sure, we have read the history about the black plague, small pox, and the Spanish flu pandemics, but vicarious experience through books and film is no substitute for first-hand experience. We now have that experience. It was sobering to see the novel SARS-CoV-2 virus ravage country after country while medical experts played a desperate game of catch-up to learn how to retard the spread of a brand new virus and how to treat the brand new COVID-19 disease it spawned. It was sobering seeing and hearing about people we know get very ill and sometimes die, and sobering reading the statistics of millions of deaths that occurred worldwide.

While most of us today have not seen such a pandemic wild-fire before, we have seen other, more smoldering pandemics that do not spread as fast. HIV is a good example. It too is a world-wide disease that, for many years was a death sentence for those who were infected. Now it is a well-managed chronic disease, thanks to medical science.

The world was not as frantic over HIV and AIDS as we were over CoV-2 and COVID. The reasons for this are probably two-fold: First, it was quickly recognized that AIDS was largely limited to homosexual men and IV drug users and, therefore, was not an eminent threat to most of us. It was not necessary to quarantine, mask up, and shut down businesses and schools in order to prevent catching the “gay disease.” Second, despite the world-wide spread of AIDS, it is not easy to catch. You must be in very intimate contact with an infected person to catch it—it is not caught by simply breathing the same air as an infected person like COVID is. Clearly, not all pandemics are created equal. Some smolder like AIDS, others fulminate like COVID. What will our next pandemic be like?

As the global population grows, as the climate changes, as humans push into spaces occupied by wild animals, and as we continue enjoying our ever increasing global connectedness, future pandemics become more likely. We are not guaranteed the luxury of facing just one a century, or even one at a time. As greatly encouraging, even exciting as it was to watch the post-molecular BioX science, as I have called it, roar into life to produce several effective and novel anti-CoV-2 vaccines in record time, there is no guarantee BioX can save us next time.

Well, the “next pandemic” already is upon us and BioX is struggling to deal with it. This pandemic is not as volatile as COVID or the Spanish flu. In fact, compared to COVID, it is a “slow mo’” pandemic, more like AIDS. But, it promises to be more difficult than COVID, even for BioX, to mitigate. It currently kills about 700,000 people annually around the world, but threatens to kill 10 million people a year by 2050 (in contrast, COVID killed ~6 million around the world in 2.5 years).

The problem

 In March 1942, Anne Miller of New Haven, Connecticut, was near death. A bacterial infection had made its way into her bloodstream, which was a death sentence at that time. Desperate to save her, doctors administered an experimental drug called penicillin, which Alexander Fleming accidentally discovered 14 years earlier. In just hours, she recovered, becoming the first person to ever be saved by an antibiotic. Rather than dying in her thirties, Mrs. Miller lived to be 90 years old and Fleming went on to win the Nobel Prize for his inadvertent discovery.

Today, decades later, germs like the one that infected Mrs. Miller, but easily eradicated with antibiotics, are increasingly becoming resistant to penicillin and the many other antibiotics that have since been developed. There is a very good chance that right now, you have such a “superbug” in or on your body—a resistant germ that, given the opportunity could enthusiastically sicken you leaving medical people at a loss on how to treat you. You would be at the mercy of the bug just as all patients with a microbial infection were before Mrs. Miller.

We are not talking about a new, exotic germ like CoV-2 suddenly appearing and ravishing the world. The antimicrobial resistance crisis stems from the simple fact that new antibiotic development cannot keep pace with the rate that common microbes become resistant to antibiotics. This very slowly growing pandemic we are now in involves run-of-the-mill pathogens, bacteria and fungi that have caused disease since humans first dragged their knuckles on the earth. These are bugs which we had well controlled with antibacterial and antifungal drugs, but there is a very definite trend toward these germs becoming resistant to ALL known antimicrobial medicines we have. Infection with multidrug resistant pathogens is the slow moving pandemic that already is among us but that is growing at a logarithmic rate.

Since multi-drug-resistant infections do not respond to our antibiotics, treatment increasingly involves surgically removing an infected organ. For example, in the case of drug-resistant Clostridioides difficile (aka, “C-diff) colitis, an emergency colectomy is performed when patients no longer respond to antibiotic therapy. CDC data show C-diff infections occur in half a million patients each year, and at least 29,000 die within one month of initial diagnosis. Up to 30% of patients with severe C-diff colitis develop sepsis require emergency surgery, and still their mortality remains high.

As of 2019, about 18 drug resistant pathogens affected >3 million people in the US, causing 48,000 deaths. These bugs cause pneumonia, septic shock, various GI problems, STDs, urinary tract infections, typhoid fever, TB, and infection with the so-called “flesh eating bacteria.” Compared to COVID, this has received relatively little attention in the popular press, but has been a frequent topic in medical lectures and conferences for the last 20 or more years. These infectious disease lectures tend to scare the bejeebers out my colleagues and me. This smoldering pandemic is that serious.

And it is not just antibiotic-resistant bacteria we have to worry about. Certain fungi, especially of the Candida genus, cause various serious ailments in people. Recently, for the first time, the CDC reported five unrelated cases (two in DC and three in Texas) of people infected with fungi that showed “de novo” resistance to all drugs. Usually, drug resistant fungi only appear after infected patients have been treated with antifungals. But, the patients in these five de novo cases had no prior exposure to antifungal drugs. The fungi were already drug-resistant when they infected the patients; they were picked up from the environment already resistant to our medicines.

Antibiotic resistance is now one of the biggest threats to global health. It occurs naturally in naturally occurring pathogens, but is accelerated by overuse of antibiotics in humans and animals, especially farm animals. What happens is that upon treatment with an antibiotic, a single infectious bug out of a population of millions or billions fortuitously mutates and becomes resistant to the antibiotic. The antibiotic then kills off all the non-resistant population, including beneficial bacteria, opening the door for the drug-resistant pathogen to take over. This resistance can occur via many different mechanisms. The bacteria or fungal cell can stop taking up the drug, it can spit out the drug if it is taken up, it can neutralize the drug once it takes it up, or it can change its internal machinery so that it no longer responds to the drug. This problem can be further exacerbated since bacteria and fungi can pass along their mutations by sharing mobile genetic material with their progeny and even with other bugs in their immediate environment that have never been exposed to the antibiotic. They can even pass along this DNA to microbes of different species. Bacteria can also pick up DNA remnants left over from dead germs. Thus, DNA that confers resistance to anti-microbial drugs can spread to the environment even in treated human and animal waste contaminating lakes and streams and ground water.

Currently, the major problem with drug resistant infections occurs in in-patient clinical settings—perhaps you have seen the heightened infection control efforts (gowns, gloves, masks, and isolation) in hospitals designed to prevent the spread of untreatable pathogens. People receiving health care, especially those with weakened immune systems, are at higher risk for getting an infection. Routine procedures, such as bladder catheterization or kidney dialysis are common ways to introduce drug resistant germs into clinical patients. But, infection can happen in any surgical or invasive procedure. Treatment of diabetes, cancer, and organ transplantation can weaken a person’s immune system making them even more susceptible for infections that either are, or that can become drug resistant.

But, antibiotic infections can also occur in the community outside of clinical settings. There is the case of Mike who needed a month long hospital stay for kidney failure after bringing home a new puppy from which he caught a multidrug-resistant Campylobacter infection. He was one of 113 people across 17 states who was part of an outbreak linked to pet store puppies. He recovered after surgery to remove a dead section of his stomach.

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The NIH Hospital Experience. About 10 years ago, the NIH Clinical Center in Bethesda was hit with an epidemic of drug resistant infections that killed a number of patients in just a few months. It was such an intractable problem that NIH finally had to gas rooms with a disinfectant, rip out plumbing, and build a wall to isolate infected patients. Still, over a period of six months it reached 17 patients, 11 of whom died. In this case, the bug was Klebsiella pneumoniae, which arrived in June 2011 with a 43-year-old female lung transplant patient who had just transferred from New York City. NIH nurses noted something startling in her chart: She was carrying an antibiotic-resistant infection.

Desperately trying to contain the superbug before it could spread, the NIH staff quickly isolated the woman in the ICU. Staff members donned disposable gowns and gloves before entering her room and her nurses cared for no other patients. After a month, the patient was discharged and the staff believed that their containment measures had worked. There were no signs that the bacteria had spread. But a few weeks later, they were shocked when a second patient tested positive for resistant Klebsiella. A third and fourth soon followed and all these patients died.

This pattern was baffling since, if the bug had not been cleared, it should have reappeared sooner. Even though it was the same type of bacteria, K. pneumoniae, perhaps it had spontaneously arisen anew in the other three patients. But by reading the genomes of the bacteria isolated from each patient, including the NYC transfer, scientists at NIH’s National Human Genome Research Institute saw that the bacteria in the subsequent patients came from the New York patient.

That meant two unsettling things: The bacteria lingered for weeks unnoticed in the hospital environment; and the hospital’s infection control measures for the New York patient failed. A further search for the bacteria found it on a ventilator that had been bleached twice. They also found it in a sink drain in a patient’s room, so they tore out all the plumbing. Yet, it began popping up it in more patients, at a rate of about one per week.

As hospital staff desperately raced to stanch the outbreak, they also struggled to treat the infected patients. Out of desperation, doctors battling the deadly, drug-resistant superbug turned to colistin, an antibiotic of last resort. It is not a new drug, having been discovered in 1949 in a beaker of fermenting bacteria in Japan. It had quickly fallen out of favor then since it causes significant kidney damage. The fact that the doctors resorted to such an old, dangerous drug highlights the lack of new antibiotics coming out of the pharmaceutical pipeline even in the face of a global epidemic of hospital-acquired bugs that quickly grow resistant to our toughest drugs.

While colistin defeated the superbug in a few patients, in at least four, the bacteria evolved so rapidly it outran colistin, too. Those four died. This was when the wall was built and all new Klebsiella-positive patients were moved into a new isolation unit behind the wall. Blood pressure cuffs and other normally reusable gear were tossed after one use. Clinical monitors were hired to follow doctors and nurses around to ensure that they were donning gowns, gloves and masks, and scrubbing their hands after seeing each patient.

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Among the most concerning mutating bacteria are carbapenem-resistant Enterobacteriaceae (CRE). Enterobacteriaceae are a large family of more than 70 bacteria that includes the common E. coli, that normally live in the digestive system and help digest food. But, if conditions allow the bacteria to leave the digestive system, they can cause serious disease that needs to be treated with antibiotics. They too can quickly develop resistance to front-line drugs and become a serious problem.  Carbapenem is an antibiotic "drug of last resort" used to treat disease caused by bacteria resistant to other front line antibiotics. Therefore, CRE are resistant to all or nearly all antibiotics and kill up to half the >13,000 patients who get bloodstream infections from them. The CDC first detected this type of antibiotic-resistant bacteria in 2000. Since then, it has been reported in 41 states. In the 10 years between 2001 and 2011, the percentage of Enterobacteriaceae resistant to antibiotics increased almost fourfold according to the CDC. Recently, the CDC tracked one type of CRE from a single health-care facility to facilities in at least 42 states.

The cause

The antimicrobial resistance crisis stems from the simple fact that new antibiotic development cannot keep pace with the rate that bacteria become resistant to antibiotics. Between 1945 and 1968, drug companies invented 13 new categories of antibiotics. Between 1968 and today, just two new categories of antibiotics have arrived. In 1980, the FDA approved 4-5 new antibiotics a year, but now only about 1-2 new drugs are submitted annually for approval. Hence, the solution appears quite simple: Develop more novel antibiotics. However, this is quite complicated since BioX science, which led to the rapid development of the novel mRNA anti-COVID vaccines, has not quite caught up to novel antibiotic development. There are two general reasons for this. First, finding a drug that disrupts the metabolism of bacteria or fungi, but that does not interfere with mammalian biochemical pathways is a difficult and narrow path. Second, so far, the market for novel antibiotics has been comparatively small, meaning that the profit incentive for pharma companies has not been large compared to that for so-called lifestyle medications. While a new antibiotic may bring in a billion dollars over its lifetime, a drug for heart disease may net $10 billion. Drugs to treat depression and erectile dysfunction are typically taken for years making them much more profitable than antibiotics that are used short-term.

Development of bact resistance

Even if we could develop new antibiotics faster, their overuse is the primary driver of antibiotic resistance. According to the CDC, in 2018 seven antibiotic prescriptions were written for every 10 Americans. Of these, one-third were unnecessary, and very often were prescribed for viral illnesses that do not respond to antibiotics. Clinicians writing these prescriptions argue that the antibiotic can help prevent the primary viral infection from leading to a secondary bacterial infection. In other words, many antibiotics are prescribed for prophylaxis rather than treatment.

Time to resistance

The number of new antibiotics that the FDA approves annually has slowed to a trickle, while the rate of bacterial mutation has grown exponentially. It used to take 21 years on average for bacteria to become resistant when antibiotics were first used. Now it takes just 1 year for bacteria to develop drug resistance because antibiotics are so readily prescribed and used. Today, the CDC lists 18 different types of antibiotic-resistant bacteria, five of which are classified as urgent threats to human health.

Physician-prescribed antibiotics, however, are not the only, or even main, source of our antibiotic resistance crisis. In the U.S., 70%-80% of all antibiotics are given to animals, especially farm animals destined for human consumption.  Drug-resistant pathogens from farm animals can spread to the environment providing a gateway through which drug resistant germs can quickly spread across our communities, food supply, and even our soil and water around the world.

Surprisingly, antibiotic use is even rampant in salmon and other fish farms, which is especially concerning, considering that 90% of fresh salmon eaten in the U.S. comes from such farms. Antibiotic-resistant infections also affect petting zoo animals, which can then transfer the germs to people.

The solution

Antibiotics clearly have been miracle medicines, saving countless lives; however, anytime they are used, they drive the development of antibiotic resistant pathogens that ultimately defeat their purpose.  Developing new antimicrobial drugs to counter the growing resistance to current drugs is not working; it is not keeping pace with the appearance of new antibiotic resistant germs. Without drastic changes in the science and economics behind antibiotic development and business, this will only be a partial solution to the growing pandemic. However, what we can do now is resort to low-tech, less expensive, and more innovative mitigation measures. These include alternative prevention steps such as more judicious use of antibiotics and increased use of isolation and sanitation measures (where have we heard this before?). Isolation and sanitation defenses against infectious diseases have been part of our disease fighting repertoire since the earliest awareness that contagions can spread through communities. It is an ancient remedy, but still the most effective way to protect ourselves against contagious diseases worldwide. Between 2013-2019, these mitigation measures led to an 18% reduction in US deaths from drug resistant infections. It always is better to prevent than treat.

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Alternative medical treatment and prevention options.  Besides the obvious masks, gloves, sanitation, and quarantine measures, there are other alternative medical (i.e., non-antibiotic) options that can be used to prevent and control drug resistant infection. In fact, these methods are often preferable to using antibiotics, which also deplete the microbiome of “good bacteria” that are critical for good health. These options include vaccines, therapeutic antibodies, and bacteriophages.

From 2000 to 2016, members of the WHO increased the use of the pneumococcal vaccine around the world, thereby decreasing antibiotic use which slowed the development of antibiotic resistant S. pneumoniae saving ~250,000 children from death. Pneumonia caused by secondary infection with other bacteria is a leading cause of complications and death in patients who get the flu. Therefore, the influenza vaccines also are effective tools to decrease the risk of drug-resistant bacterial pneumonias by preventing viral influenza. Since patients with COVID can also develop secondary complications from bacterial pneumonia, COVID vaccination now is another important weapon in the arsenal to prevent the development of antibiotic resistant bacterial lung infection.  

In recent years, healthcare providers also have been increasingly using therapeutic antibodies to treat viral and bacterial infection. For example, antibody therapy is often used to treat recurrent C-diff GI infections, and antibodies to prevent and treat bacterial associated pneumonia also are being developed. So far, we have not seen bacteria develop resistance to antibodies.

Finally, a different and very novel approach to dealing with untreatable bacterial infection has recently taken advantage of bacteriophages, which are viruses that can specifically infect and kill bacteria. There are a few cases in which phage therapy has been used to cure people dying of multidrug-resistant bacterial infections.  According to Pew Charitable Trusts, as of June 2019, 29 non-antibiotic products like therapeutic antibodies and phages were in clinical development and seven were in Phase 3 clinical trials. 

Perhaps BioX is indeed coming to rescue us from the growing pandemic of drug-resistant pathogens.

Notes: 1) By way of disclaimer, your correspondent has consulted for a biotech company that engages in “big genome” research to search for novel antibiotic molecules produced by everyday bacteria and fungi that grow in the soil under your feet. Something like this could be part of the future of novel antibiotic development. 2) In order to have blog updates delivered to your email, see the simple Subscription Instructions here. Remember, you can easily unsubscribe when you want. But, you can’t beat the price.


COVID More Deadly Than Flu For Kids

In the US, nearly six times more kids and teens died from COVID in one year than did from the flu, according to a new analysis of pediatric mortality data. According to CDC data, childhood flu deaths have ranged from 39 to 199 per year since 2004. Meanwhile, in 2021 alone, more than 600 children died from Covid-19, according to an analysis done by researchers at the Harvard University Medical School and at Brigham and Women’s Hospital in Boston.  The analysis used data from the CDC to compare COVID deaths during the pandemic to flu deaths over the last decade (see figure below).

Of the known respiratory viruses, only CoV-2 has ever killed more than 100 US kids in a single month since the middle of the 20th century. Much of that is because we have long had vaccines for other viruses that cause human respiratory disease, but have yet to widely vaccinate children against COVID-19. Hopefully, new vaccines will also render COVID less deadly for kids like vaccines have done for several other respiratory diseases.

Throughout the pandemic, some have argued that COVID poses little health risk to kids aside from a few days of sniffles. Though kids often experience less-severe symptoms than adults, COVID is still a very real risk. An estimated half a million kids now deal with long COVID, a number that experts say is likely an undercount because its myriad symptoms make it tricky to diagnose.

Mortality in kids


What Happened To The Flu And Other Respiratory Diseases?

A NYC based travel blogger who travels a lot used to get a respiratory infection whenever she flew. That stopped when the airline mask mandates went into effect. The mandates, of course, were designed to hinder the spread of the CoV-2 virus that causes COVID, but it makes sense that if masks and other physical (that is, non-medical) mandates worked to mitigate COVID, then we would see a decrease in other contagious respiratory diseases after the mandates were, well…mandated.

We did.

The mandates worked, despite persistent claims of some to the contrary. This particular blog subject was stimulated by a radio talk show where a couple of nonscientist talking heads announced that there was no scientific proof that the masks or other mandates prevented disease. I previously posted in these pages evidence that masks, in particular, do indeed work to retard the spread of disease (see here, here, here, and here). In this post, I present further data on how the mandates significantly reduced the incidence of other infectious respiratory diseases around the world. If the measures can reduce flu, then you can bet that they also reduced COVID-19.

Note, however, that this is not necessarily an endorsement for returning to the measures. Your humble scribe didn’t much like his glasses fogging up, or having to make two trips from the car to the store because he forgot his mask. But, let’s argue the issue based on its merits and not from false premises based on incorrect claims.

After South Korea implemented various hygiene and social distancing measures in response to COVID, they saw the 2019-20 flu season end an astounding 12 weeks earlier than the previous year. Epidemiological surveillance data bolstered by clinical diagnostic testing showed that infection from several different pathogenic respiratory viruses (including adenovirus, bocavirus, metapneumovirus, rhinovirus, flu, parainfluenza, and respiratory syncytial virus) dropped to nearly 0% just five weeks into 2020!

In the United States, the incidence of infection by influenza, respiratory adenovirus, rhinovirus, enterovirus, RSV, non-COVID coronaviruses, metapneumovirus, and parainfluenza viruses all decreased in March 2020, soon after implementation of mandates. Similar results were seen in Japan.

More dramatically, since pandemic mitigation measures were put in place, there has been a 99% global reduction of infections from both influenza types A and B compared to prior years. In particular, one of two flu B substrains has not been isolated in the world since August 2021 suggesting that this variant is now extinct. The overall genetic diversity of influenza viruses has also dramatically diminished indicating that other flu sub-types (or clades) have disappeared around the world since the pandemic mandates were put in place.

And this reduction of respiratory infectious disease does not only hold for those caused by viruses. Another study looked at surveillance data from 26 countries across 6 continents for several bacterial diseases caused by Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, which are typically transmitted via respiratory droplets. Numbers of weekly cases in 2020 were compared with corresponding data for 2018 and 2019. Data for disease due to Streptococcus agalactiae, a non-respiratory pathogen, were also collected from nine laboratories for comparison. All countries experienced a significant and sustained reduction in respiratory bacterial diseases in early 2020 (Jan 1 to May 31), coinciding with the introduction of non-medical COVID containment measures in each country. By contrast, the incidence of disease due to S agalactiae (which is not transmitted by the respiratory route) did not differ significantly from the 2 previous years.

Clearly, the mandates significantly reduced the incidence of respiratory infections by non-COVID viruses and bacteria. They worked. So, why did we still have COVID infections after the mandates went into place? The mandates reduced, not eliminated these diseases, so infections still happened. Since we did not have historical COVID infection data from previous years to compare with, the effects of the current mandates on the incidence of COVID are not as clear cut as they are with other diseases for which we do have historical data for comparison. But, as I wrote before (see above), it is clear that places in the US and around the world that used masks and other protective measures saw reduced incidence of COVID compared to similar places that did not.

Bottom line: The studies mentioned here regarding non-COVID infectious diseases fully support data previously posted in these pages that the mandates, including masks, are effective non-medical tools for controlling infectious respiratory diseases.

Don’t let anyone tell you differently.


Gain-Of-Function Viral Research: What’s The Big Deal?

Senator Rand Paul and many others have raked Dr. Anthony Fauci, long-time director of the National Institute for Allergy and Infectious Diseases (NIAID), over the coals for supporting research at the Wuhan Institute of Virology, and especially for supporting “gain-of-function” (GoF) research at that facility.

This needs some ‘splaining.

First, Senator Paul and the anti-Fauci crowd need to give us their definition of GoF research and then explain why it is bad. If they mean research that gives viruses new capabilities, then most labs seeking to learn how a virus functions is guilty. For example, University of Wisconsin flu researcher, Yoshi Kawaoka, did research that exchanged genes from the 1918 H1N1 Spanish flu virus with less virulent H1N1 viruses in order to learn why the Spanish flu caused so much death back then. That is classical gain-of-function research and it was done under strict quarantine and safety conditions (disclaimer, your blogger was on the safety review committee that vetted and approved Kawaoka’s Spanish flu research). It is legitimate and important research.

The Wuhan Institute of Virology had a small bit of indirect funding from Fauci’s NIAID to support a genetic registry of coronavirus sequences that is freely available to all researchers around the world. As new coronaviruses were discovered and their genomes sequenced, the lab investigators cataloged them. They also inserted the new spike protein genetic sequences into incipient, harmless viruses to see how well the new spike proteins allowed a virus to infect mammalian cells in tissue culture. This was done to help assess how much of a risk a new coronavirus was for spreading among mammals. Strictly defined, this research gave the engineered test viruses new capabilities—they acquired new spike proteins and gained the new functions that came with that. This is legitimate research and not some nefarious plot to weaponize coronaviruses that Rand Paul, et al., dishonestly allude to in their allegations.

Furthermore, there are the thousands of other labs around the world, including mine at UCLA and the University of Wisconsin that use viruses as tools for gene transfer in order to study the activity of newly discovered genes. For example, my lab discovered an aberrant gene that was associated with a particular human leukemia that used to be untreatable. We wanted to learn how the abnormal gene affected blood cells, so we cloned it and inserted it into a virus that could infect mouse cells. We then gave mice leukemia by infecting them with a virus that expressed a human cancer gene. That recombinant virus gained the function of the human cancer gene. Rand Paul, et al., would call that sinister gain-of-function virus research. However, from that and other research, that incurable leukemia now is 95% curable. Sinister?

Sure, using modern molecular technology, a minacious actor could help a pathogen gain super-lethal function and develop a super-pathogen, or a weaponized bug, like antibiotic resistant anthrax or super-spreading Ebola virus. It would be pretty easy to do. But, by far, the GoF research routinely done in labs around the world is done for learning not for killing.

When Paul accuses Fauci of supporting GoF research, that accusation is attached, without evidence, to an implicit accusation that the Wuhan labs are creating more virulent pathogens for nefarious reasons. So, why does Paul not go after Kawaoka or me for using NIH money to create viruses that might be able to kill people (Kawaoka’s flu construct) or that could cause cancer (my virus expressing a human cancer gene)?  

Could it be for political reasons?


Lions And Tigers And…Deer? Oh My!

First it was bats and humans, then domestic cats and dogs, farmed mink, and big zoo cats; now gorillas, hippos, and wild deer that have been infected by the SARS-CoV-2 (CoV-2 for short) virus. Many of these animals have become ill and several have died of COVID-19, most recently three snow leopards in South Dakota and Nebraska zoos. This is quite a wanton virus.

Of course, before CoV-2 and COVID-19 were known to the world, we knew that bats, humans and a few other animals, notably civets and even camels, were ready hosts of several different strains of “‘rona” viruses. We also knew that domesticated animals are also susceptible to their own coronavirus diseases—in fact veterinary coronavirus vaccines have been in use for years. Humans are known hosts for several coronaviruses, including those that cause the common cold, as well as the viruses that cause SARS, MERS, and now COVID-19. And we know that humans often catch these germs from bats and other intermediate hosts as diverse as civets and camels. After we genetically identified CoV-2 and were able to follow its spread, we quickly noticed that domestic pets also could be infected. This was closely followed with news that seven big cats at the Bronx zoo had become infected, and that mink farms across Europe were hotbeds for CoV-2 spread between humans and the animals and back. In fact, mink farms became such a hotbed of CoV-2 zoonotic spread that a couple of European countries completely shut down mink farming and culled all their animals. Several US states have also sharply curtailed mink farming. PETA probably applauds.

More recently two snow leopards at the Lincoln, NE children’s zoo and one in a zoo in South Dakota died from COVID. The Lincoln zoo also had two infected Sumatran tigers who recovered after being treated with steroids and antibiotics to prevent secondary infections and pneumonia. How the animals were infected is uncertain, but the most likely scenario is that they caught the virus from a caretaker. The problem is, none of the caretakers tested positive for the virus. Bats? Something else?

Since April 2020, when a tiger tested positive at the Bronx Zoo, dozens of other animals in zoos around the world have caught COVID. This month, the Denver Zoo reported the first coronavirus cases in hyenas, and the St. Louis Zoo found eight positive cases among its big cats, including two snow leopards. Abroad, the virus has killed a lion in India and two tiger cubs in Pakistan. Big cats seem especially susceptible since three other snow leopards at the Louisville Zoo were infected last December, and another snow leopard tested positive at the San Diego Zoo in July. The virus doesn’t just infect our fuzzy friends either; two hippos, named Imani and Hermien, at a zoo in Antwerp recently tested positive for COVID-19. Zoo keepers were first alerted to a potential problem when they noticed that the colossi had “runny noses.”  One reckons that a runny nose for a hippo is a big deal. One also wonders who gets to dab that nasal maw in order to test for the virus.

In fact, zoo and domestic animal infections have become so prevalent that an animal COVID vaccine developed by Zoetis, a NJ-based veterinary pharma company and former Pfizer subsidiary, has been authorized by the USDA for experimental use. The Cincinnati Zoo, for one, has vaccinated  80 animals, from giraffes to apes, against COVID.

Deer too. Oh my! It is one thing for zoo animals to acquire COVID—their captivity makes it easy to limit their interaction with other animals and humans to prevent spread of contagions, and they seldom complain that their rights are being infringed when they are quarantined. However, COVID in wild animals is a different story, as we have seen with bats and how easily they transmit the virus to humans. Scientists now have evidence that CoV-2 also readily propagates in white-tailed deer. In fact, the virus is already widespread in cervids across the US, which likely has significant implications for the long-term course of this pandemic.

In September of last year, genetic analysis of the gene that encodes the ACE2 protein (i.e., the viral receptors expressed on many cells in the body) in many different animal species suggested that CoV-2 could easily infect deer (and several other animals too). A survey of white-tailed deer in the Northeast and Midwest found that 40% had antibodies against the CoV-2 virus, indicating prior exposure. Between April and December 2020, veterinarians at Penn State found active CoV-2 infections in ~30% of deer tested across Iowa. Then during the winter COVID surge in humans from Nov. 23, 2020, to Jan. 10 of this year, ~80% of the tested deer were infected. The prevalence of the virus in deer was 50 to 100 times greater than in Iowa residents at the time (and the deer reportedly did not wear face masks). The study, published about two months ago, indicates that white-tailed deer have become a permanent reservoir for CoV-2. While it is not fully understood how the virus entered the deer population, genetic sequence analysis of nearly 100 viral samples found that the variants circulating in deer matched the variants circulating in people. This suggests that deer caught the virus from people multiple times in Iowa alone. How that happens is not known since people usually do not have close contact with live deer. More concerning is whether viral variants arising in deer readily pass back to people.

Bottom line. Clearly, a lot of different animal species can catch Cov-2 and spread it. It is clear that people can spread coronaviruses to pets and other animals, but the FDA says that the reverse, animal-to-human virus transmission, is not common. But, it clearly happens as we have seen with this pandemic, and with many other viruses that cause SARS, MERS, AIDS, Ebola, flu, etc., that spread from animals to humans. The prevalence of CoV-2 infection in so many species of mammals, especially in animals that have close contact with humans, suggests that several animal species, not just bats, can serve as permanent reservoirs for the virus and the jump to humans is something that can happen over and over. This is not unprecedented. It is what we see with influenza, which is carried back and forth between the Northern and Southern hemispheres with migratory birds, in which different flu viruses shuffle their genomes to create the new strains of flu for which we have to vaccinate against each year. This animal reservoir for flu makes it next to impossible to eliminate influenza, and similar animal hosts for CoV-2 likely would make it nigh impossible to eliminate COVID too. I raised this specter some months ago in these pages when reporting that pet dogs and cats can carry the virus. Our furry friends represent a viral reservoir that is in even closer contact with people than bats, deer, and fortunately, hippos and leopards.

We also have to be worried about the CoV-2 virus mutating in the different animal species that harbor and spread it. We know that happens in bats, which makes it almost certain that new strains of the virus will arise in deer and dogs too. We have already seen this on mink farms in the Netherlands and Poland. Farmworkers passed the virus to captive animals where it spread, mutated, and then spilled back into humans. In fact, zoonotic transmission from animals to humans probably happens thousands of times a year. Researchers from the EcoHealth Alliance and from Duke-NUS Medical School in Singapore, estimate that each year many people are newly infected with SARS-related coronaviruses. Many may get sick, but there are many reasons why most of these infections never grow into noticeable outbreaks (for example see my earlier blog post about unusual respiratory infection clusters in China and Los Angeles just before COVID). The researchers also created a detailed map of Asian habitats of 23 bat species known to harbor SARS-related coronaviruses then overlaid it with data on where humans live to create a map of potential infection hot spots. They found that close to 500 million people live in areas where bat-to-human transfer is likely, and this risk is highest in southern China, Vietnam, Cambodia, and Indonesia. Other surveys done before COVID-19 showed that many people in Southeast Asia harbor antibodies against other SARS-related coronaviruses. Blending these data with data on how often people encounter bats and how long antibodies remain in the blood, the researchers calculated that ~400,000 undetected human infections with these viruses occur each year across the region.

That is just for bat-to-human transfer in Southern Asia. It now looks like we will have to also concern ourselves with zoonotic coronavirus transfer from Buddy and Bambi too.

For this reason, researchers are working to develop a universal coronavirus vaccine that will be effective against most viral strains and variants. I will write about this soon. Stay tuned.

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Lessons for COVID Vaccinations And Herd Immunity From Influenza And Rubella

Note: The following is modified from the blog post, “Rubella: We vaccinate for far less,” by Katelyn Jetelina, MPS, PhD who is an “epidemiologist, biostatistian, professor, researcher, wife, and mom of two little girls.” She writes a blog entitled, “Your Local Epidemiologist.”

 “Those who cannot learn from history are doomed to repeat it.”

 George Santayana

 

In the US, more than 300,000 kids aged 5-11 have been vaccinated with the Pfizer COVID-19 vaccine, which has proven that the vaccine is safe and can benefit some kids. It prevents infection, COVID-19 disease, death, long COVID-19, and keeps kids in school. Admittedly, only a few kids develop serious COVID disease and fewer have died from it. Most infected kids only have mild, if any, symptoms. Vaccine skeptics use this fact to stridently argue against childhood COVID vaccines. So, why are we pushing to vaccinate children who rarely get seriously ill?

There are two reasons why we vaccinate anyone. The first reason is to protect the vax recipient from the disease; this is an individual-level benefit of the vaccine. The second is to protect a larger population by trying to retard disease spread; this is a population-level benefit of vaccines that is better known as herd immunity.

But, anti-vaxers only focus on the fact that childhood vaccines provide little individual-level benefit to children and wholly ignore the larger population-level benefit of the vaccines. As I have written before, vaccinating children who are at low risk for serious disease is still very important for reducing viral spread in order to  prevent more dangerous viral mutants from emerging. It also is important for reducing infection and disease in more vulnerable people in the population. It is these population-level benefits that are the most important reason to vaccinate low-risk children. Vaccinating children for a population-level benefit, rather than for individual-level benefit, is not at all new and is a very acceptable practice. Here are a couple of examples.

Influenza: A few decades ago, Japan mandated flu vaccines for all school kids. That vaccine slowed the spread of flu in schools leading to many fewer student illnesses and absences. More significantly, vaccinating all school kids also caused a sharp drop in flu deaths in older people like school teachers and staff, parents, and grandparents who have close contact with the kids.

Kids are walking incubators for respiratory viruses and readily spread their germs to others. Infected children essentially are virus vectors much like mosquitoes are vectors for malaria and yellow fever. Therefore, in Japan, the flu vaccine effectively shut down a major vector of influenza infection for at-risk older people. That is an undeniable and important population-level benefit of vaccinating school kids against the flu.

Rubella: Now, let us take a deeper dive into rubella, or German measles, and its vaccine, which is the “R” in the MMR shot. It is especially enlightening to compare the natural history of rubella to what we are learning about COVID-19.

Both COVID and rubella are caused by airborne viruses that spread when infected people cough, sneeze, or even talk. As with COVID, rubella symptoms in children are quite mild. They include its tell-tale measles-like rash, sore throat, low grade fever, mild pink eye, and general discomfort. But, about 25 to 50% of infected children will not experience any symptoms. Likewise, many CoV-2 infected kids also do not develop symptoms. But, asymptomatic kids infected with either rubella or CoV-2 readily spread their viruses to friends and family; hence, they can be significant vectors delivering both viruses to people at-risk for serious disease.

Over the last two years, we have learned that COVID mostly (with significant exceptions) causes serious illness and death in older people or for those with certain other health conditions. Similarly, while rubella only causes mild disease in most children, it is incredibly dangerous for developing fetuses. A woman infected with rubella during the first 3 months of pregnancy has a 90% chance that the fetus either will not survive or will develop Congenital Rubella Syndrome (CRS), characterized by deafness, blindness, heart defects, and/or severe brain damage. In the early 1960s, a rubella outbreak began in Europe and spread to the US. In 1964-65 ~12.5 million total cases were reported in America affecting nearly 50,000 pregnancies. More than 11,000 of the infected mothers miscarried, or delivered still-born babies. Of the >20,000 infants born alive to infected mothers, the majority had severe illnesses: 2,100 died shortly after birth, 12,000 were deaf, 3,580 were blind, and 1,800 had permanent mental disabilities.

The rubella outbreak proved hard to contain because, as with COVID, infected asymptomatic people make it hard to know when someone is spreading the virus. Rubella also is just as contagious as COVID. Both viruses have an R0 = 6-7 meaning that each infected person will infect, on average, 6-7 other people. For comparison, flu’s R0 = 2-3, which means it is about half as contagious as the other two viruses. It, therefore, is not surprising that like rubella, the COVID outbreak is proving hard to contain.

Soon after the 1960s rubella pandemic began, a safe and effective vaccine was quickly developed and approved for use in Europe and North America (this is reminiscent of the quick development of the COVID vaccines). Early on, there was a robust international debate on who should get the rubella vaccine. There were two schools of thought:

  1. Despite the fact that rubella only caused mild problems in kids, some proposed vaccinating all children hoping to provide indirect population-level protection for pregnant women and their at-risk fetuses.
  2. Others argued that because children were only minimally affected they should not be subjected to the vaccine and that only women of childbearing age should be vaccinated. This, proponents argued, would more specifically protect those most at risk.

Ultimately, it was found that countries that chose #2 were not able to sufficiently reduce the virus, because it still spread unfettered among children. This strategy did not reduce the rates of CRS. Eventually, option #1, vaccinating low-risk children (like what we are moving toward with the COVID vaccine) was adopted world-wide. Vaccination rates of school kids reached ~85% in the US, which last experienced a serious rubella outbreak in 1995. In 2004, transmission of rubella was eliminated in the United States and in 2015, it was eliminated in all the countries of North and South America.

Soon, the MMR vaccination was mandated for children in all 50 states. It is important to realize that these mandates were not to protect kids from the mild disease but to protect the at-risk population, or fetuses. In other words, we vaccinate kids against rubella not so much to protect them, but to provide a significant population-level benefit to others.

Today, because of broad rubella vaccination of low-risk children, we see an annual average of just 10-15 cases of CRS in the US that are traced back to international travel to countries with poor rubella vaccination rates. In contrast, in countries with low vaccination rates, about 120,000 children are born each year with severe CRS birth defects and even more die in utero.

Bottom Line: This country, and indeed all of the Americas and most of Europe came together to eliminate endemic rubella through broad population-level vaccination programs targeting low-risk groups responsible for spreading the virus to the high risk population. Japan saw the same effect with influenza. They focused on broadly vaccinating a low-risk population (school kids) and saw great benefits in the high-risk older population. As we approach a broad COVID vaccination strategy that includes giving the shot to low-risk children, it very likely will have a population-level benefit and help protect those most at-risk for serious disease.

It is important to note that the population-benefit conferred by the COVID vaccine also applies to all of us and not just to children. When we are vaccinated, not only does it protect us, it also provides significant protection to at-risk people around us. That, in fact, is called “herd immunity.”

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