Covid Shots Targeting Delta May Be Needed, Researchers Say

Vaccines targeting the highly transmissible delta variant may now be needed, given its ability to infect people with fading immunity and potentially increased severity, researchers leading a large English study of Covid shots said.

A third wave of English cases has been driven by the delta strain among both unvaccinated people -- especially those aged 12 to 24 -- as well as some people who had received Covid shots, according to authors of a study of samples from about 98,000 people in England. The effectiveness of vaccines at stopping infection during the study period fell to 49%, the researchers estimated, down from 64% in a month earlier. Vaccines’ protection against development of Covid symptoms was 59%, down from 83%.