Vying With Viral Variants
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The back story: There are four known CoV-2 variants in the US that are more transmissible than the parent strain. They are the UK variant, which is 70% more infectious and 60% more deadly than the original strain. There also are Californian and Brazilian variants that are more transmissible, but it is not yet known if they are more deadly. However, in Brazil, their variant is associated with a significant increase in infections and ICU stays for young, healthy, unvaccinated people. Fortunately, the current vaccines seem to be effective at preventing infection with these strains.
More worrisome is the South African variant that is 50% more transmissible. It is worrisome because the AstraZeneca vaccine is not very effective against this variant, and a very recent, but a small study out of Israel suggests that the Pfizer vax might have reduced efficacy against the S. African variant. It is not yet known if this strain causes more serious disease. These findings provide evidence that mutation can produce new viral strains that can evade the immune response to the viral spike protein.
Two other variants, the so-called New York variant, and a second Brazilian variant have early signs of being more infectious or even being able to reinfect people who previously had COVID-19. Data are still being collected in order to better understand the risk that these variants pose. Stay tuned.
You can follow the variants in the US here.
The bottom line is that the world is in a race to roll out vaccines faster than troubling virus variants can arise. The UK is expected to reach herd immunity early next week. Infections there dropped by 60% during March, with deaths dropping more rapidly, indicating that the vaccines are helping prevent severe illness and viral spread. Meanwhile, the US leads the world in total vaccines administered (175 million), with 43% of the adult population having received at least one shot. More than 700 million doses have been administered world-wide.
The major concern is that a too-slow vaccine distribution, such as what has happened in Brazil, will encourage more virulent variants to arise. If we don’t quickly achieve herd immunity across the world, it probably will just be a matter of time before a variant arose that renders the current vaccines useless, and we would have to start over.
What is a world to do? Besides increasing surveillance of viral variants, a couple more prevention initiatives are in the works. One is economic and the other scientific.
Economics of viral mitigation: The economic approach is detailed in an article by the Associated Press Economics Writer, Martin Crutsinger. Basically, the International Monetary Fund (IMF) proposes giving $650 million to support vulnerable countries struggling to deal with a global pandemic. Along with that, the Group of 20 major industrial countries issued a joint statement that announced a six-month moratorium on debt payments by 73 of the world’s poorest countries.
The rationale behind these actions is to ensure that poor countries, where vaccinations are lagging due to lack of resources and infrastructure, can pick up the pace of vaccination. Their lag in rolling out shots is a threat to the whole world, even while wealthy countries are approaching herd immunity. In order to beat the variants, vaccines are needed to quickly create herd immunity and stop viral spread before a variant that can avoid vaccine immunity appears. When countries lag in vaccinations, the virus continues to spread increasing the chance for an immune-avoiding variant to pop up. Such a variant can then spread to countries that are highly vaccinated, starting the pandemic over again because the current vaccines would be ineffective. We would be back at square one.
Science to the rescue: So far, all the vaccines, except one from China, which uses the whole virus, direct the immune response to the viral spike protein that is used to attach to receptors on the surface of cells in your body. The viral variants we are concerned about show mutations in the spike protein that allow them to become more infectious, and in one case, to be less affected by some of the vaccines. In addition to trying to nip the virus in the bud by quickly building world-wide herd immunity, new vaccine strategies are being developed to quickly respond to newly arising CoV-2 variants, and even to respond to entirely new strains of viruses that will arise in the future.
- One way to do this is to begin developing booster shots as soon as a coronavirus variant becomes a significant concern. With the new mRNA, and adenovirus vaccine delivery technology, this is eminently possible. It just requires scientists around the world being vigilant for new variants. Pfizer, Moderna, AstraZeneca, and Johnson & Johnson have all said they’re starting work on developing booster shots to the known variants.
- Last week, the US government announced a pact with CureVac to tackle variants, pairing artificial intelligence to predict future mutations that can be quickly addressed with modern vaccine technology. London-based GlaxoSmithKline is also working with CureVac on mutant-quelling vaccines.
- Another strategy is to identify viral molecules other than the spike protein that the immune system can recognize. Efforts are underway to test the immunogenicity of what is called the CoV-2 nucleocapsid, or N protein, which wraps itself around the viral RNA. If successful, future vaccines could incorporate both the N and S (or spike) proteins, which would require the virus to mutate both of those genes in order to avoid vaccine-induced immunity, a greatly tougher task for the virus.
- Researchers at Moderna, Novavax, and the University of Oxford are designing multivalent vaccine strategies to protect against multiple CoV-2 variants with a single shot, and even against new viruses that might emerge in the future. A similar strategy is used with the annual flu vaccine, which usually incorporates four different influenza strains in one shot. It is also used with measles, mumps, and rubella vaccines. Some vaccines against pneumonia target as many as 23 variants of that pathogen.
- Finally, a wholly new vaccine technology has shown recent success in animal studies. It works by chemically attaching many short viral protein sequences from different CoV-2 variants, and even from completely different coronaviruses, to engineered nanoparticles that are then injected. In mice, this single vaccine induced an antibody response capable of neutralizing many different coronavirus strains. If successful, this could represent a universal vaccine capable of neutralizing CoV-2 and its variants, as well as other coronaviruses such as SARS and MERS with a single vaccine. And it can be easily modified to quickly respond to future viral epidemics caused by novel coronaviruses or other viruses that will certainly arise. The technology is being developed at Cal Tech using technology developed by collaborators at Oxford University. The nanoparticle platform is a “cage” made from 60 identical proteins. Each of those proteins has a small protein tag that functions like a piece of Velcro to which the viral protein sequences stick resulting in a vaccine nanoparticle with short protein sequences from four to eight distinct coronavirus strains on its surface. If successful, this could prevent infection and disease for several different viruses with a single shot.
We are in a revolutionary era of vaccinology. BioX marches on.
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