Mar 08 2021

COVID Race Against Time

We know a lot more now about SARS-CoV-2 and COVID-19 than we did a year ago when this pandemic was just getting into full swing. One of the big questions was about the emergence of new variants – how fast does the virus mutate, and what is the probability of variants with new properties emerging? Scientists have been tracking the variants since the beginning. It’s actually a good way to track the spread of the virus, and our ability to sequence the genome of specific viruses is fairly advanced.

As of August 2020 scientists had identified six strains or variants of SARS-CoV-2, without any significant difference in biological function among them. This was encouraging – the hope was that this virus mutates slowly and that no functionally new versions would emerge. This is important for two reasons. The first is the question of whether or not someone who has already suffered COVID-19 or been infected without symptoms could become reinfected. This is partly about the strength of the immune response to infection, but also about whether or not new strains would be able to bypass immunity to older strains.

However, by the beginning of 2021 two things were happening, one good, one bad. Vaccine distribution was ramping up. Several vaccines were approved toward the end of 2020 and while initial distribution was slow, it is speeding up. By now almost 59 million Americans have received at least one dose of a vaccine, and we are being promised availability for everyone who wants a vaccine by May. At the same time daily new cases of COVID are dropping fast, although still relatively high compared to the Spring and Summer of 2020.

But the bad news is that three new variants of SARS-CoV-2 have now been identified that are functionally different – one identified in the UK, one in South Africa, and one in Brazil. These variants have several mutations affecting the structure of the spike protein that gives coronavirus its name, and is responsible for its ability to infect cells. Spike proteins are also a target of antibodies produced by infection or vaccine. As news about these variants comes dripping it, it’s not good. All three appear to be more infectious. They spread more easily than the older variants, which means more robust protection might be necessary to prevent spread. Further, because of their increased infectivity, they are rapidly becoming the dominant strains where they spread.

The other and perhaps even more important question is whether or not the available vaccines will be effective against these new variants. There is some concerning new on this front. A recent study found that antibodies from both infection and vaccination are less effective against the Brazil and South Africa variants:

The B.1.1.7 (U.K.) variant could be neutralized with similar levels of antibodies as were needed to neutralize the original virus. But the other two variants required from 3.5 to 10 times as much antibody for neutralization.

There is also evidence that the Brazil variant can reinfect people who were previously infected by an older variant. It seems that the current vaccines are still effective against these new variants, but perhaps not as effective against the Brazil and South Africa variants. What does all this mean?

Time will tell, but it likely means that we are in a race against time. The more a virus spreads, the more it makes copies of itself. Each copy is a roll of the dice, an opportunity for a mutation to occur. Most mutations will be silent or not have any significant consequence. Some may even be harmful to the virus. But occasionally a mutation will be favorable, making the virus more infectious, more deadly, or better able to evade the immune system. Viruses with favorable mutations will tend to dominate over those with neutral or harmful mutations – that’s evolution 101. And then, of course, you get variants of the new variants, and some of those may be worse still. The longer this pandemic simmers along, the greater the chance of even worse variants emerging.

This is one more reason why it is important to shut down this pandemic as quickly as possible. That will not only save lives and allow the resumption of more normal economic and other activity, but will reduce the chance of new variants emerging. It may come right down to the wire between herd immunity and the emergence of fully resistant variants. If a highly resistant variant does emerge, then it could extend the pandemic by 6-12 months. It would also mean that we would need to update the vaccines to account for the new variants, and everyone would need to get a second vaccine. That, too, would be another race against time and still further variants. We may settle into SARS-CoV-2 becoming endemic, like the flu, and needing to get a vaccine every year to cover the new variants.

This all means that now is not the time to let up on efforts to control the pandemic. It is not over, and in fact we may be entering the most critical phase yet. We need to reduce spread as much as possible to slow the emergence and spread of new variants, to give us time to get everyone vaccinated. Of course, everyone is tired of this pandemic and the restrictions that are in place, and there is real harm being done to industries, education, and mental health. But the harm will be greater if we don’t head off new variants before it’s too late.


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