Coronavirus news & views

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.

A Single Gene Doubles Risk Of COVID Death

“Nothing shocks me. I’m a scientist.” —Indiana Jones

British scientists recently identified an allele, or a version of a gene, that portends lung failure and death in COVID-19 patients. Research recently published in the journal Nature Genetics, found that a poorly studied gene expressed in lungs, designated LZTFL1, has a variant form that does not differ in its coding sequence. That is, the different alleles of the gene express the same protein sequence. They do differ, however, in their non-coding sequences that regulate expression of the gene. When expressed, the gene product prevents cells lining airways and the lungs from responding properly to the CoV-2 virus. The lining of the lung essentially transforms into less specialized cells which affects their normal function.

Previous work had identified a stretch of DNA on human chromosome 3 that doubled the risk of death from COVID. Using an artificial intelligence algorithm to analyze millions of genetic sequences from hundreds of cell types from all parts of the body, the Oxford University Howard Hughes research team honed in on the lung-specific genetic off-on switch. This is another example of what I previously labeled "BioX," the new frontier of bioscience, or post-molecular biology science.

Importantly, the variant allele that augurs a worse lung response to infection does not affect the immune system. Therefore, the it is probable that vaccination remains the best way to protect these at-risk patients. Finding this new allele could also lead to novel therapies to target the pathway affected by this genetic variant to provide targeted treatment for at-risk populations.

The troublesome variant is mostly found in people of South Asian ancestry—some 60% of whom carry the allele—which partly explains the severe devastation from COVID seen in the Indian subcontinent. In contrast, 15% of those with European ancestry and 2% of Afro-Caribbean people carry the risky allele.

It will be interesting to see if this lung-specific gene also affects the course of other respiratory infectious diseases.

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Lingering Post-COVID Vascular Risks

George Burns once opined that “the secret of a good sermon is to have a good beginning and a good ending; and to have the two as close together as possible.” The same might be said for blogs. If so, this is a pretty good blog post.

We have known for some time that patients with COVID-19 are at risk for dangerous blood clots (also called deep vein thrombosis, or DVT), pulmonary embolism, and bleeding. Findings reported this month in the British Medical Journal reveal that this risk continues several months after COVID recovery.

The study compared more than one million people in Sweden who had COVID-19 to a control group of more than 4 million people who did not. The overall risks for each problem were low, but still elevated for up to six months following COVID. According to the report, DVT occurred in 0.04% of patients who had had COVID and in just 0.01% of control patients during the same time. Pulmonary embolism occurred in 0.17% of post-COVID patients and in 0.004% of control patients. And bleeding events occurred in 0.10% of patients who had recovered from COVID, while only 0.04% of control patients had such a problem.

While the risks of blood clots and bleeding were highest in patients whose COVID had been more severe, those who had had mild COVID still showed an elevated risk.

Bottom line: You are not out of the woods after you recover from COVID. Significant problems can arise a few months later.

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COVID-Diabetes Link Confirmed

As I penned in these virtual pages almost a year ago, COVID survivors have a high risk for developing diabetes. Early on, diabetes was identified as a risk factor for severe COVID illness, but two years later, scientists were surprised by the unforseen reverse correlation between COVID and the metabolic condition. The increased risk for diabetes in COVID survivors was recently confirmed by US and German scientists.

A study of more than 180,000 American veterans done at the St. Louis VA Health Care System found that COVID survivors were 40% more likely to get a new diagnosis of diabetes within a year of their COVID diagnosis than a control group of veterans who avoided the virus. That works out to about 13.5 extra cases of diabetes per 1,000 COVID patients.

The increased risk for diabetes was evident even in people who had a low risk of diabetes before COVID, and the likelihood of newly diagnosed diabetes increased with the level of care patients received for COVID. In other words, the sicker the patients were with COVID, the more likely they were to develop diabetes.

The other study from Germany found that people who had mild COVID cases were 28% more likely to be diagnosed with type 2 diabetes compared to a control group consisting of patients who had an upper respiratory tract infection caused by a different bug. That study was based on an analysis of electronic records from a nationwide primary care database that followed patients, including almost 36,000 COVID cases, for 3-5 months. This means that these newly diagnosed cases of diabetes arose quickly after COVID infection, and were not a result of general respiratory infection, but were a specific consequence of CoV-2 infection.

Questions remain about whether diabetes that follows COVID is just temporary and reversible after patients fully recover, or whether it leads to chronic disease. In other words, if you had even mild COVID, you should ask your doctor to screen you for diabetes, which simply entails a fasting blood draw to test for glucose and hemoglobin A1c levels, which are elevated in diabetic patients.

A lingering question is how COVID leads to diabetes. Does the virus directly affect the insulin-secreting beta cells in the islets of the pancreas, or is new-onset diabetes caused by metabolic changes in fat cells which we know are readily infected by the virus. It is also possible that insulin production is perturbed by viral damage to the cells that line vessels supplying blood to the pancreas, indirectly causing death of insulin producing cells. A more trivial cause for post-COVID diabetes could simply be an unveiling of incipient diabetes that might have gone undiagnosed because people have been away from the health-care system during the pandemic. It is also possible that steroid medications prescribed to tame the COVID inflammatory response could elevate glucose levels in the blood, leading to a diabetes diagnosis.

Research into the cause of the COVID-diabetes link continues apace—stay tuned.

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Why Don’t The COVID Vaccines Last Longer?

The FDA just authorized a second booster shot of the Pfizer-BioNTech and Moderna coronavirus vaccines for people over 50 and the CDC has approved it. A second booster has already been approved in the U.K., Sweden, Israel and Denmark.

Why do we need a second booster only months after the first booster, which came only months after most of us received two jabs of either the Pfizer-BioNTech or Moderna mRNA vaccines? Are the vaccines not very good? After all, we get small pox or measles shots that last a lifetime. Others, like the vax for tetanus, last for ~10 years. Why can’t we get a more durable coronavirus vaccine?

The answer is complicated and largely rooted in both viral biology and vaccine immunology.

Viral biology. The simplest answer is that viral mutation can change the molecules the vaccine immune response is trained to recognize, causing vax immunity to decay as viruses mutate. The coronavirus vaccines are directed against the spike protein expressed on the original CoV-2 that first appeared in Wuhan, but that ancestral bug has spawned mutated progeny that look a bit different to the immune system. In other words, viral variants created by “antigenic drift” become less recognizable to the immune system. That is why the vaccines are somewhat less effective against the Omicron variant that carries numerous point mutations in its spike protein. The current vaccines are still pretty effective against current viral variants, but continued antigenic drift along with the selection of variants that can better avoid vaccine immunity will likely require new vaccines in the future.

So, why do we need new flu vaccines every year, and need frequent CoV-2 vaccines, but we don’t similarly need new measles vaccines? Measles, mumps, flu, COVID, and other diseases are caused by viruses, but the different viruses behave quite differently. Viruses carry relatively little genetic material that tends to mutate as they replicate and spread. Some viruses, like flu, also have a “segmented genome” meaning that their genetic material is carried on several separate genetic molecules, making it easy to shuffle their genomes like a deck of cards when different flu strains infect the same animal. Other pathogens carry all their genetic material on a single DNA or RNA molecule making such gene shuffling between strains less likely, but it still happens. Also, the mutation rate of a pathogen’s genome is a function of its replication rate; hence, each time a bug copies its genome, small random errors are inserted into its genetic code. The more the bug replicates, the more mutations will accumulate in its genome and the faster replicating bugs will more rapidly create new variants. Thus, the measles virus is pretty stable since it does not replicate as much as a coronavirus or a flu virus, so it is not surprising that vaccine immunity to measles is much more durable. Smallpox and polioviruses also have relatively low replication rates and vaccine immunity to them also is long-lasting. In contrast, flu and coronaviruses replicate rapidly and pass back and forth between humans and animals. This means that they mutate rapidly and need frequent vaccine updates.

Other vaccines, such as the TB vax, target bacteria not viruses. Bacteria carry larger genomes that are not so changeable, so anti-bacteria vaccines also are pretty long-lasting compared to many anti-viral vaccines.

Yet other vaccines, such as those against tetanus, diphtheria, and pertussis do not even target the pathogen at all, but target toxins produced by the bugs. Vaccinated people produce antibodies that neutralize the toxins and this prevents disease. These vaccines do not forestall infection, they simply prevent the ill effects of the pathogen. Therefore, for these toxoid vaccines, there is no immunological selective pressure to select pathogen variants that can avoid vax immunity. Vaccines against these toxins also tend to be among the longest-lived vaccines.

Vaccine immunology. Vaccines aim to mimic natural immunity we develop to infection with pathogens. By exposing the body to harmless imitations of a pathogen, vaccines create an immune response and immune memory against pathogens, while avoiding the disease caused by the bugs. When an infection does occur in a vaccinated person, a rapid and robust immune response is mounted, first with B-cell generated antibodies that latch onto the invaders and prevent them from spreading and causing illness. Then T-cells secret cytokines that further ramp up the inflammatory response, and other T cells attack pathogen-infected cells. As explained earlier in these pages, antibody responses tend to linger only a few weeks to a few months and then gradually decay. This is good; otherwise your blood serum would be like syrup from all the antibodies against all foreign things you encountered over your lifetime. While antibodies circulating in your blood are good for quickly attacking infections shortly after infection, they do not confer long-term immunity. What confers long-term protection is what are called memory cells. These are a relatively few T and B cells that go dormant after fighting an initial infection or responding to a vaccine, but hang around awaiting a new infection to signal them to quickly roar back to life and mount a vigorous response against their cognate pathogen. This secondary response to a previously seen pathogen is much faster and usually nips the bug in the bud so you don’t even know you were infected.

When we hear that CoV-2 immunity decays only a few months after vaccination, the reports usually refer to declining levels of anti-CoV-2 antibodies, which happens naturally. Such announcements do not take into account your immune memory, which is harder to measure, but which is a better metric of your long term immunity. The problem also is that we simply have not had enough time with the vaccines to know how long their immune memory persists. It seems relevant that a study published in July 2020 reported that people who were infected with SARS in 2003 maintained robust T cell immunity 17 years later. So far, indications are that even though antibody levels fall over time, immunological memory after vaccination also remains robust. This is seen by the continued protection from serious disease and death in vaccinated people with low antibody levels. The vaccines and the immune memory they stimulate are working. How long that memory persists is unknown. Time will tell.

So why are we getting the booster shots? In the face of a raging pandemic caused by a novel pathogen, the cautious approach is to keep antibody levels at a protective level in vaccinated people until we better understand the extent of long-term protection brought on by our immune memory. The boosters, therefore, represent a cautious approach to maintain an effective antibody defense during these still early months of a novel pandemic. We likely will reach a time where world-wide immunity from vaccination and natural infection will give us baseline protection that will render COVID-19 mostly a bothersome disease rather than a life threatening infection. Until then, the boosters are a good idea to help us maintain an effective antibody defense against serious disease.

The natural pathology of measles is instructive here. Even though antibody levels typically decline after most immunizations, antibodies produced after a measles vaccine persist for many years. This happens with some other, but not all, vaccines too, but why? In countries where the measles virus is endemic, repeated infection of vaccinated people keeps the antibody immune response in continual high gear. That is not the case with the flu virus which changes rapidly and bypasses last years shot. Interestingly, measles has been eradicated from the US and Western Europe, so vaccinated people are not continually exposed and re-exposed to the virus and, unlike for those who live in endemic areas, our anti-measles antibody levels decline. Therefore, our long-term protection against the virus is due to our immune memory and not due to antibody levels.

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Updated: Over 65? Roll Up Your Sleeve Again

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The Washington Post just reported that Pfizer and its partner-in-vax, BioNTech, plan to seek emergency authorization for a second CoV-2 booster for those of us 65 and older (you know who you are). It is intended to beef up immunity that wanes a bit a few months following the previous booster.

US data show protection against severe COVID illness is robust after the first booster, but falls somewhat from 91 percent effective in preventing severe illness to 78 percent effective over several months. Still, 78% protection is very good, but given how transmissible Omicron is, and the possible emergence of the Son-of-Omicron, which might be even more infectious and virulent, the idea behind a second booster is to offer people the chance to acquire the greatest level of protection possible. Not a bad idea.

The data that will be submitted to the FDA in support of the 2^nd booster probably will include real-world data collected in Israel, which has already rolled out the second shot, and has reduced infections and serious illness in people older than 60. This will likely not be the last CoV-2 vax we will see. Pfizer and BioNTech are also working on a vaccine more effective against all variants and provide more lasting protection. That remains on the horizon, so stay tuned.

For those of us 65 and older, we (at least the males in that demographic) remember draft cards. As we entered our later years, the draft card, if unburned, was replaced in our wallets with our AARP cards, and then accompanied with our Medicare cards. Now we need a new wallet pocket to accommodate our vax card.

On a personal note about cards, your maturing and slowing bloggeur admits favoring a certain grocery store in town because they still card him when he buys his bottles of 80 proof anti-vax remedies.

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Update: Three days after this was first posted, Moderna announced that it also has asked for FDA approval for a second booster. However, they ask that the booster be approved for all adults over 18, and not just for those over 65 as Pfizer/BioNTech have done. This request, like the one submitted by Pfizer/BioNTech is largely based on recent data from Israel. 

Moderna made a strategic decision to request approval for all adults in order to give the FDA flexibility in deciding which patients would be good candidates for the booster. In other words, they could decide that it also would benefit under 65 and so recommend.

 

 

“Mater Artium Necessitas”

So said William Horman, 16^th century Headmaster of the Eton school. Translated, he posited, “The mother of invention is necessity.”

And necessity these days means environmental screening for SARS-CoV-2. Room air samplers have been developed and used to detect airborne virus RNA in large settings, such as hospitals and other large buildings people frequent. In fact active environmental air samplers have been used outdoors to detect airborne DNA and RNA as a way to survey animal populations in the wild. These are fairly large, immobile, active air samplers that require electricity to power them and crews to maintain them. While useful, environmental samplers are limited by their power requirements, lack of mobility, cost, and maintenance needs.

So, the mother of invention led to a portable, passive, personal air sampler that can be worn on one’s collar tool as described in a recent paper. It was reported to be quite effective for detecting ambient exposure to aerosol and droplet CoV-2 in the air.

The device uses a polydimethylsiloxane (PDMS)-based passive air sampler, which previously has been used to capture hydrophobic chemical contaminants and other nonpolar compounds, such as lipid-enveloped viruses that stick to the polymeric surface. After laboratory testing under controlled conditions that determined the unit could detect sub-infectious levels of virus exposure, samplers were passed out to select community members across Connecticut to surveil personal CoV-2 exposure. The study reported that 21% of wearers working in indoor restaurant settings, and 9% working in homeless shelters were exposed to 4-112 copies of CoV-2 per cubic meter of air. No exposure was reported for healthcare workers or “community members” who did not work in putative high-risk environments. The authors surmised that the lack of exposure by healthcare workers was due to the strict sterilization and hygiene procedures used in clinics and hospitals.

While the monitors did a good job sampling ambient air in real time, the need to later analyze the sample by RT-PCR for the presence of viral particles means that the results are not obtained in real time. This is a bit of a drawback to the current personal samplers.

Bottom line. These PDMS-based passive samplers may serve as a useful exposure assessment tool for airborne viral exposure in real-world high-risk settings and allow early detection of potential cases and guidance on infection control. More broadly, this also could be used to monitor the presence of other biological scourges in public places and serve as early warning devices for biological warfare threats.

Necessity is indeed the mother of invention.

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Still More Evidence For An Animal Origin Of The Virus

Conspiracy buffs won’t like this, but compelling new evidence presented in three papers, which include photographic and DNA data, has pretty much nailed down the origin of the SARS-CoV-2 virus. It began in a wet market animal not in the lab eight miles away as the conspiracists have conjectured. This new data comes from an international team of scientists which concluded that the coronavirus twice jumped from  caged wild animals into people at the Huanan Seafood Wholesale Market in Wuhan. These data correlate nicely with previous geo-epidemiological data showing the market, not the lab, to be the infection nidus with later infections radiating out from there.

Despite the Chinese’s government denial that live animals were sold in the Wuhan market, the new studies provide photographic evidence of wild animals sitting in stacked cages in the market in late 2019, in or near stalls where scientists found SARS-CoV-2 virus on a number of surfaces, including on cages, carts and machines that process animals after they are slaughtered at the market. This, along with a new genetic analysis pinpoints a specific stall at the market where the virus passed from an animal into people. These data also estimate the time when not just one but two zoonotic spillovers occurred, once in late November or early December and then again few weeks later. This coincides almost exactly with the timing of the outbreak of disease at and around the market.

The two initial infection events involved slightly different versions of the SARS-CoV-2 virus. The fact that they were related is evidence that the virus had spread and mutated in animals in the market before it infected humans.

A leader of two of the studies was U of Arizona professor, Michael Worobey, a viral pandemic sleuth who has been at the forefront of the search for the origins of the bug responsible for the current pandemic. His lead in the research is significant since, back in May, 2021, Worobey, along with 17 other scientists, called for investigation into the lab-leak theory. His latest research overturned that conjecture. This new evidence adds to previous evidence for an animal/market origin of the virus presented earlier in these pages here and here.

Final thought. It is sobering to think how these two simple infection events that occurred in November and December of 2019 in a Chinese market triggered something that has now caused six million deaths and untold misery around the world. And it is not finished with us.

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Son Of Omicron

“A rose is a rose is a rose.” –Gertrude Stein

Omicron is Omicron is Omicron (except when it becomes something different).

Two-plus years into the pandemic, many Americans are ready to declare the COVID crisis over. But, we have been at this juncture before—at the end of the very first surge (remember “flattening the curve?”), and again as Delta faded. Each time, a new virus variant came roaring back. Why should it be different now?

There are reports of two new sons of Omicron circulating in the world. The original Omicron, or BA.1 has spawned BA.2 and BA.3. While little is known about BA.3 at this time, very early indications are that BA.2 represents an even more infectious variant of Omicron, and it is spreading around the world and the US. This variant of a variant seems to be about 30% more infectious than Omicron BA.1. It quickly overtook BA.1 in South Africa and other countries and has caused a second Omicron surge in Denmark. BA.2 has been detected in 74 countries, and has become dominant in at least 10 of them: Bangladesh, Brunei, China, Denmark, Guam, India, Montenegro, Nepal, Pakistan and the Philippines, according to the World Health Organization's weekly epidemiological report.

In the US, BA.2 has been reported in 47 states and accounts for ~4% of all new infections according to the CDC, and it appears to be doubling fast. Samuel Scarpino, director of pathogen surveillance at the Rockefeller Foundation says that if infections double again to 8%, we will be in another exponential growth phase, or the fifth wave of the pandemic. In other words, BA.2 seems to be quickly backfilling the vacuum left as BA.1 peters out.

While BA.2 clearly arose from BA.1, it carries dozens of additional gene changes, making BA.2 as distinct from BA.1 as the Alpha, Beta, Gamma and Delta variants were from each other. This suggests that BA.2 might soon be given its own unique Greek letter designation.

What does BA.2 augur? While vaccination and prior infection still appear to protect fairly well against BA.2, this variant still seems more adept at skirting the immune system then the original Omicron. An early report also shows that vaccine induced antibodies often fail to neutralize BA.2 in tissue culture, and that the virus better replicates than BA.1 in nasal epithelial cell cultures. Nevertheless, those who have been vaccinated and boosted are 74% less likely to become ill from BA.2.

Hopefully, this reduced immunity will still be enough to provide an immunological redoubt against extensive spread of BA.2. The best thing that could happen is that as we become increasingly immunized by vaccine and infection, it might be enough to continue the drop in BA.1 Omicron infections, and check any surge from the new BA.2 variant. This is speculation at this point, and one thing we have learned over the last 2+ years is that the virus does not often respond as expected.

Then there is this: Very preliminary laboratory data hint that BA.2 might cause more severe disease than BA.1, and it appears capable of foiling some of the key weapons we have against COVID-19. In initial lab studies, a Japanese team reported that BA.2 has structural features that might make it as virulent as Delta was. This prediction of increased virulence was supported by hamster infection experiments, but this has yet to be confirmed or refuted in real-life epidemiological studies. Rest assured, those studies are underway, so we will see.

BA.2 also is almost completely resistant to some COVID treatments, such as sotrovimab, a monoclonal antibody therapy that is currently used against Omicron.

Bottom line: During the Spanish flu, as people wearied of the social restrictions designed to prevent the spread of the virus (there were no vaccines or drugs for flu then), many pushed back against the restrictions, which led to premature relaxation of the mandates. Cities like Denver and Philadelphia, which lifted their mandates early paid a hefty price. Other cities like St. Louis, which took a more cautious approach were relatively unscathed. Let’s hope that we are not relaxing and entering a “control phase” too quickly.

What’s ahead of us is not COVID’s end, but might be the start of a phase in which we continue to invest in measures to continue to shrink the virus’s burden. Success in this is not entirely up to us. The virus will have a say too. Our future will depend both on the virus’s continued and unpredictable evolution and on our responses, both immunological and social. The goal is to get ahead of any new variants with wide spread immunity and a growing formulary of antibody and drug treatments, and, yes, this might also require renewed mandates.

A detailed report  looking at past suspected coronavirus pandemics (e.g., the Russian “flu”of 1889, which was probably a coronavirus) published last August in the journal Microbial Biotechnology, suggested plausible scenarios in which elevated levels of COVID-19 deaths could last another five years or longer. This of course depends on what happens to and after BA.2.

It probably is not quite time to relax all mask mandates or let up on the push to vaccinate.

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COVID And Heart Disease—It’s All Relative

A new COVID study recently reported in Nature got the attention of your aging scrivener. It reported that COVID-19 increases risk for cardiovascular disease for at least a year after infection.  This was a large study of US veterans that found that the risk of having a heart attack, stroke or several other cardiovascular events was higher for those who had COVID-19 the year prior compared to those who weren’t infected. The risk was highest for those who had been hospitalized but was still elevated for those not admitted.

But when you read about elevated risk in the news or especially on social media, what does it mean? Hint: the media usually will not tell you this.

In order to understand the significance of such risk, we need to know both the relative and absolute risks. Relative risk is what we often see reported in alarming headlines—for example in this case, the risk of a heart attack was reported to be 63% higher in those who had had COVID-19. That is relative risk and it sounds pretty bad, right? Relative risk tells us that a risk is higher in one group than in another, but it doesn’t tell us the whole story. To put relative risk in perspective, we also need to know the absolute risk of the bad thing happening.

For example: let’s say that in a group of 100,000 “normal” people, one is expected to develop a rare cancer. But in people who were recently x-rayed, two people in 100,000 develop the cancer. The headlines would scream that x-rays caused a 100% increase of the cancer. The risk doubled after being x-rayed. Pretty chilling. Yet, the absolute risk in this example is extremely small—only one extra person out of 100,000 who are x-rayed gets the cancer.

Compare that to a situation where 10,000 out of 100,000 typically develop this cancer and x-rays again double the risk. That means 20,000 out of 100,000 people getting x-rays will get the cancer. In the two scenarios, the relative risk is identical—x-rays are associated with a doubling of cancer cases—a 100% increase in cancer risk. But in the second example, the absolute risk is much, much greater. Instead of causing cancer in only one out of 100,000 people (0.001%) as in the first example, the second example has x-rays causing cancer in 10,000 of every 100,000 people, or 10%.

Going back to the study in Nature, remember having COVID led to a 63% increased chance of having a heart attack. The data showed that the absolute risk of heart attack was 4.67/1000 for uninfected people compared to 7.59/1000 for those who had COVID-19 in the previous year. So, in absolute risk terms, an extra 3 people out of 1000 had a heart attack after having COVID-19. That puts the 63% increased relative risk in perspective.

Now that relative vs absolute risk have been explained, we are still left with the question of whether these extra three heart attacks are concerning. Like many other things, it depends how you look at it.

With tens of millions of people getting infected with COVID-19, an increase of three heart attacks for every thousand people can add up fast. Looking at the population level, this could lead to a noticeable rise in cardiovascular disease burden and lead health experts to begin planning for a wave of heart attacks. But, looking at the individual level, most COVID infected peoples’ risk of having a heart attack in the next year is pretty low. So, if you have COVID, you do not need to begin planning your funeral.

Bottom line: These alarming headlines need to be understood in terms of relative vs absolute risk and then looked at in terms of the effect on the population vs on the individual. Way too often during this pandemic, I have seen folks abusing both. For example, how often do you hear people saying that COVID is overblown because <1% die from it. This totally ignores the absolute risk (how many deaths is that) and focuses only on the individual effect while totally ignoring the population level effect (1% of 100 million is a lot of people).

It is all relatively absolute and absolutely relative.

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