Epidemiologists have found that the Indian strain of SARS-CoV-2 has recently almost displaced the British variety from the United States. It now accounts for more than half of the new COVID-19 infections.
“The proportion of infections with the British version of coronavirus among new infections in just six weeks has fallen from 70% in April this year to 42%. It is being replaced by the Indian and Brazilian variations of SARS-CoV-2. Moreover, the first one is spreading across the United States significantly faster than the second one, ” the researchers write.
The Indian variant of the new type of coronavirus (delta variant) is called strain B. 1.617. It appeared in India at the end of November 2020, and in the spring of this year began to spread widely throughout the rest of the world. From other varieties of SARS-CoV-2, the delta variant differs in a set of several previously unknown mutations. Presumably, these mutations increase the contagiousness of the virus and give it resistance to the action of antibodies.
American epidemiologists led by William Lee of Helix have studied in detail how the Indian strain is spreading across the United States. They analyzed almost 20,000 samples of the coronavirus that were collected in different regions of the United States between the beginning of April this year and June 15. Among them were the first cases of infection with the Indian strain of coronavirus in the United States, thanks to which scientists followed its spread in as much detail as possible.
The study found that in April, the United States was dominated by various variations of the British strain of SARS-CoV-2-they accounted for more than 70% of new cases of COVID-19 infection. In the next six weeks, the situation changed dramatically and this indicator fell to 42%. This means that now more than half of new infections are caused by the Indian strain of coronavirus.
Another “competitor” of the British version was the Brazilian strain. But it spreads more slowly than B. 1. 617. This may indicate that shortly, the delta variant will displace the Brazilian version of the virus. However, epidemiologists are still at a loss to say when this will happen.
In addition, Lee and his colleagues found significant differences in the rate of spread of new variations of SARS-CoV-2 across states with high and low vaccination rates. In their opinion, this indicates that the vaccines used in the United States effectively protect the population from new forms of coronavirus infection.