Expert view: What evolutionary biology tells us about Coronavirus mutants

The pandemic has become protracted. What had promised to be a sprint has turned out to be a marathon. And being in the sprint mode, have we gone too far in the wrong direction in what is possibly not even a marathon but a cross-country race? Has chasing the virus at all costs turned into a prestige issue for governments and their scientific advisers?

Significantly, the initial strategy of enforcing lockdowns, physical distancing and school closures, which has become a recurrent strategy, was based on a computer simulation project by a high school student, daughter of an American scientist at Sandia National Laboratories, New Mexico (US).

Similarly, studies on hamsters on benefit of masks guided the mask mandate. Subsequently, a Danish randomised trial on masks was inconclusive. However, we have come a long way since then mask-wise. The consensus presently is not a single mask, but double masks.

Panic has dictated our response to the pandemic. Citizens of almost all countries, including major democracies, have complied with measures which deprived them of their fundamental rights. A major contributor to the pandemic of panic has been the draconian measures which has no precedence in the history of public health.

Projecting number of cases and deaths of one disease out of context can easily generate panic in the population. This has never been done for any disease ever. This has resulted in mass obsessive compulsive disorder around one disease. Everything about the novel disease assumes larger than life dimensions.

In the initial days panic was caused by fear of transmission from surfaces. Presently, there are reports that air borne small particles or nuclei can be carried up to 10 metre. Cause for further panic. Conveniently overlooking that within this radius there may be millions of microbes surrounding us, in addition to the billions within us.

The latest agenda for mass hysteria are media reports of mutant variants of the novel coronavirus. Popular perception would be that mutants generate monsters. Evolutionary biology tells us otherwise. Whether we like it or not Nature does grant even viruses a fair chance. To survive, they follow nature’s way of adaptation – Darwin’s Law—by way of mutations.

It’s important to remember that lethal or virulent strains do not go far. Viruses which kill, also perish with the host. Lesser virulent ones which do not kill but cause symptoms will also phase out because of self-isolation.

The mutant strains, which will survive and go far, will therefore be the less virulent strains which do not kill the host, produce very mild symptoms or none at all. People infected with such mild variants will mix with others and transmit widely. High contagiousness does not translate to high virulence. Such strains promote population immunity with minimum casualties.

What can be the implications of mutation? There are a number of possibilities. Most mutations have no impact on virulence or infectivity. Some mutations will become less virulent but more infective, with better chances of survival and propagation by law of natural selection. And rarely, when a few become more virulent, such outliers would also lose the evolutionary race.

Will vaccines work? Will immunity obtained after recovery from natural infection work? Will RT-PCR tests detect the mutant variants?

Antibodies and immune cells generated by natural infections or vaccination act on some of the building blocks known as epitopes. The novel coronavirus has about 30,000 base pairs or building blocks of nitrogen compounds. During mutations only a few of the building blocks undergo change. So, antibodies and immune cells primed against the whole virus as on recovery from natural infection or immunisation by a vaccine derived from the whole virus have very good chance of neutralising these variants.

Some vaccines target only the spike protein or more specifically few of the building blocks in them. These targets are known as epitopes, out of 3000-4000 of these base pairs in the spike protein. If mutation occurs in an epitope in the spike protein, there is slightly more chance of antibodies and immune cells hitting a blank on a mutated epitope.

However, as many epitopes are involved in the process, such vaccines will also confer some protection against the mutants. The RT-PCR tests which target a number of epitopes should also detect variants.

It should also be somewhat reassuring that due to principles of evolutionary biology, mutants which will dominate at the population level in the long run will be less virulent. This is the way of all pandemics. Over time they become seasonal minor illnesses.

The concept is best summed up in a dialogue from a popular Hindi Movie Agneepath, “Apna ussool kehta hai jab dushman ki umar badh jaaye toh usse dosti kar lo... apni umar badh jaati hai.” Translated, “My principle is, when the life of your enemy increases then befriend him…it increases your life too.”

[Author’s note: Technical concepts and terms have been oversimplified for better understanding]

(The writer is professor and Head, Community Medicine, DY Patil Medical College, Pune)