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This week has been a period of stocktaking for major scientific communities and, sadly, a period of heightened denial for many of our leaders. A July 30, 2021 report from the UK’s Scientific Advisory Group for Emergencies (SAGE) postulated the likely future direction of the COVID-19 pandemic. In this report, 4 possible scenarios are discussed.
Scenario 1 is that the virus can become more virulent. This can occur either by a combination of point mutations or by the recombination of variants (essentially two variants combining into one). We must remember that SARS-CoV, the virus that caused the 2003 outbreak, has a case fatality rate of around 10% and also uses the ACE2 receptor in cell entry. MERS-CoV, another related coronavirus, has a higher death rate, but uses a different receptor. Thus, it is possible that SARS-CoV-2, the pathogen that causes COVID-19, undergoes extensive mutations to become more virulent while maintaining its infectivity.
Scenario 2 is that a variant may escape the vaccines. There are 3 proposed mechanisms, all of which can occur.
The first, and, according to the report, “almost certain” is a variant which avoids the vaccine by a gradual accumulation of point mutations or antigenic drift. Unfortunately, we have a few disturbing variations that might have accomplished this by now. Our current Delta variant has almost escaped the effectiveness of vaccines, but the lambda variant can be even more problematic. Kei Sato, PhD, University of Tokyo and one of the 2 lead authors of a study conducted by researchers at the University of Tokyo, said that “Lambda may be a potential threat to human society.”
As reported by Kimura I, et al., “A recent article also suggested that vaccines effectively prevented COVID-19 in Chile (Jara et al., 2021). Nonetheless, a strong outbreak of COVID-19 occurred in Chile in the spring of 2021 (WHO, 2021b), suggesting that the Lambda variant is able to evade vaccine-induced antiviral immunity.
The second mechanism, which may already be starting to occur, is that the virus infects and spreads to another animal species (“a reverse zoonotic event in an animal reservoir” – SAGE). The virus then evolves separately, returning to humanity as an entirely new entity. A report from the US Department of Agriculture found that 40% of 385 samples taken from white-tailed deer in the states of Michigan, Pennsylvania, Illinois and New York were positive for SARS-CoV-2.
The authors concluded that their research shows that deer can be infected with SARS-CoV-2, spread it to other deer, and “exhibit sustained viral shedding.” More worryingly, white-tailed deer “can be abundant near urban centers”. It is very problematic; the control may involve handling and special precautions near the deer, or even possible slaughter.
The third mechanism is the recombination of 2 viruses causing rapid and extensive changes. This is one of the reasons why we need to reduce the viral spread, which makes it unlikely that an individual will be infected with 2 different variants at the same time. With MERS-CoV and SARS-CoV as examples, SARS-CoV-2 has plenty of room for significant changes to avoid immunity while maintaining infectivity.
The third scenario is the emergence of drug-resistant variants that may elude antiviral drugs. This is likely to happen and has happened in the past with monoclonal antibodies. However, with so few effective drugs, this scenario was estimated to have a medium impact on the pandemic.
The fourth scenario, the one I like the most, is that SARS-CoV-2 mutates into a less virulent form, giving natural immunity to the more virulent variants and making serious illnesses disappear. Some believe this may have happened with the Spanish Flu of 1918. For this to happen, the less virulent variant would have to be more transmissible, but that’s a pretty big hurdle to overcome with the highly infectious Delta variant. Essentially, it would become like the common cold. Unfortunately, SAGE concluded that this is “unlikely in the short term” but a “realistic possibility in the long term”.
Taken together, the SAGE report, the establishment of an animal host by viruses, and the news regarding the lambda variant is an extremely deadly mix. We need to come together as a society to slow the spread of this virus so that viral recombination occurs and genetic drift slows down. In addition, we need to formulate strategies to prevent the spread of host animals to mankind. Above all, we must learn to live with this virus so that our pharmaceutical giants can develop and manufacture vaccines faster than the virus can mutate.
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