With most viruses it takes at least a year before a new variant emerges. But the coronavirus is an exception to the rule.

The corona crisis has been going on for about two years now. And in that time, many variants of SARS-CoV-2 have already been reviewed. In the meantime, the counter stands at sixteen variants, some of which are worrisome. What scientists didn’t quite understand was why so many different variants emerged in a relatively short period of time. A new study, published in Molecular Biology and Evolutioncreates more clarity.


Usually viruses mutate at a fairly constant rate. “With most viruses, it takes at least a year for a new variant to emerge,” said researcher Sebastian Duchene. “However, what we saw in the variants of SARS-CoV-2 – particularly the variants of concern – was that they have undergone far more mutations than we would expect under the normal evolutionary rate of comparable coronaviruses. For example, the delta variant evolved from its ancestral form within six weeks.”


To understand why this happened, the researchers analyzed hundreds of genome sequences from SARS-CoV-2 strains. In this way, they hoped to better understand the mechanisms that led to the emergence of the most worrying corona variants – especially the first four: alpha, beta, gamma and delta.

At times

The investigation leads to a surprising discovery. Because the coronavirus appears to be evolving at lightning speed. The virus undergoes momentary bursts of mutations and then returns to its ‘normal’ pace. “Initially, the rate of evolution of SARS-CoV-2 was generally thought to be much higher,” Duchene says. “But now it appears that the virus is able to adjust and temporarily increase its rate of evolution. It’s like someone stepping on the gas pedal of a car.”

“It’s like someone stepping on the accelerator of a car”


It means that the rapid emergence of new corona variants can be explained by the virus’ exceptional ability to accelerate its evolutionary pace at times. This can be caused by a number of factors, including long-term infections in individuals, strong natural selection, or the high number of infections among the unvaccinated, which allows the virus to spread and evolve rapidly.

Early detection

According to the researchers, the study shows how important it is to detect new variants early. “Because this virus is evolving so quickly, early detection is extremely important,” Duchene emphasizes. “This allows us to monitor the virus closely and respond immediately.”

In addition, Duchene emphasizes how important it is to get vaccinated. “Anything we can do to make sure fewer people are carrying the coronavirus will also reduce the chances of new variants appearing,” he concludes.