Scientists say the world has reached a precarious point in the Covid-19 pandemic, one in which conditions are ripe for the emergence of several new coronavirus variants that could complicate disease control efforts.
The virus continues to spread rapidly in many parts of the world, even though certain segments of the population have gained some immunity as a result of infection or vaccination.
Scientists say the combination – high rates of viral transmission and a partially immunized population – encourages the emergence of variants that are potentially more transmissible or more lethal. More transmission means more opportunities for the virus to evolve, they say.
“If everyone has immunity, then you have almost no virus circulating and the virus cannot adapt,” said Emma Hodcroft, a molecular epidemiologist at the University of Bern, adding that if no one in a population has immunity, then there is no no pressure on the virus to evolve. “The middle part, where you have a partially vaccinated population or a partially immune population, with a lot of viruses circulating, is kind of a danger point,” she said.
The new variants could also reduce the effectiveness of Covid-19 vaccines and treatments and could lead to reinfections among people who have already recovered from Covid-19, scientists say. They say the key to minimizing these problems is social distancing and other measures to reduce the contagion, as well as stepping up vaccination efforts, which have lagged behind in many places.