The coronavirus could still burst out of control
A genomic study of the pathogen’s path of evolution explains why it’s so infectious. And the reason raises the risk of a mutation that can dodge current vaccines. Let’s act to mitigate it
It feels a lot longer, but it has only been a year or so since we first mixed horror with grim fascination over the likelihood of a virus having leapt upon us from a bat, and that too, with enough virulence to paralyse human life as we knew it. Scientists who placed SARS-CoV-2, the ‘zoonotic’ bug that is responsible for our misery, under examination are now largely settled on its origin. It hopped across from the winged nocturnal mammal suspected all along. Of special interest, however, is the genetic trajectory of the virus as it evolves within another host species (i.e. us), since this plays a major role in how we humans fare against its spread and the illness it causes. A recent study published in the journal PLOS Biology offers a plausible explanation for why covid has proven so contagious. It also cautions us on the possibility of this coronavirus evolving beyond the scope of current vaccines.
The research project in question sequenced and studied the genomes of a wide sample of coronavirus variants. The progenitor of SARS-CoV-2, it found, had already undergone significant mutations by the time it jumped to us. These genetic shifts were along a path that gave it a nasty advantage on human transmission and debilitation. “Usually, viruses that jump to a new host species take some time to acquire adaptations to be as capable as SARS-CoV-2 at spreading," in the words of Sergei Pond of Temple University, US, a co-author of the paper, “and most never make it past that stage, resulting in dead-end spillovers or localized outbreaks." The covid virus, it turns out, was pre-adapted to humans as hosts. From this, one can infer that survival pressure did not require it to change very much once it began infecting people. Terrible as its success was, there was also an upside to that. As the study observed, the pandemic’s first 11 months saw very few genetic alterations of significance to our vulnerability. Its genomic stability meant that it could be chased down by vaccines, as we have seen happen. The worry is that this reprieve might have ended. Even as we wage a vaccine war on the virus, the study suggests that its mutation curve could steepen to dodge our shots. The pathogen is seen to be diverging from its January 2020 form that was used to make the current lot of jabs in use. The discovery of variants—France is the latest to report one—has turned alarmingly frequent, of late, and there’s no saying when it will take a drastic turn. It could easily escape human control and we must act to mitigate this risk.
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The best response would be to ensure that human vaccination stays ahead of the virus’s evolution. Some countries look likely to achieve this, but India is caught in a second wave and our immunization drive is too slow for comfort. True, infections on the ascent are taking a less severe toll on us this time around, but that’s no excuse for complacency. The science of mutation tells us that the larger the gap between our jabbed and jabbed-nots, the greater the potential for the virus to mutate. We have been assured that vaccines based on messenger-RNA can be tweaked quickly to counter new versions. As of now, though, these are not available here. Nor do we know if such confidence is warranted. What we do know is that the pandemic is still alive and kicking. And that quelling it will be a long haul.
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