Do the Covid vaccines prevent you from spreading the virus, or do they just protect you from getting sick?
Scientists don’t know yet – and the uncertainty has major consequences during the introduction of the vaccines.
Pfizer and Moderna, the companies that developed the vaccines authorized in the US to date, say their vaccines are about 95% effective in preventing people from getting sick with Covid symptoms. But there is still not enough evidence that the vaccines also prevent asymptomatic infection and transmission.
The companies say research is underway to determine the answer. Without vaccines, research has suggested that asymptomatic transmission of the coronavirus that causes Covid is responsible for about a quarter of infections.
The result, experts say, is that precautions such as wearing masks, social distancing and avoiding crowded spaces will be needed until the land gets closer to herd immunity, the point where enough people are immune to a disease. make its spread unlikely. Some studies have estimated that about 75% to 80% of the U.S. population must be immune to Covid-19 in order to achieve herd immunity, but that number is a moving target and could rise as new variants emerge.