October 1. Newer variants of the coronavirus like Alpha and Delta are highly contagious, infecting far more people than the original virus. Two new studies offer a possible explanation: The virus is evolving to spread more efficiently through air.
The realization that the coronavirus is airborne indoors transformed efforts to contain the pandemic last year, igniting fiery debates about masks, social distancing and ventilation in public spaces.
Most researchers now agree that the coronavirus is mostly transmitted through large droplets that quickly sink to the floor and through much smaller ones, called aerosols, that can float over longer distances indoors and settle directly into the lungs, where the virus is most harmful.
The studies compared the Alpha variant with the original virus or other older variants. But the results may also explain why the Delta variant is so contagious — and why it displaced all other versions of the virus.
“It really indicates that the virus is evolving to become more efficient at transmitting through the air,” said Linsey Marr, an expert in airborne viruses at Virginia Tech who was not involved in either study. “I wouldn’t be surprised if, with Delta, that factor were even higher.”
The ultratransmissibility of the variants may come down to a mix of factors. It may be that lower doses of the variants are required for infection, or that the variants replicate faster, or that more of the variant virus is exhaled into aerosols — or all three.
The Alpha variant proved to be twice as transmissible as the original virus, and the Delta variant has mutations that turbocharged its contagiousness even more. As the virus continues to change, newer variants may turn out to be even more transmissible, experts said.
Source: New York Times