Do Covid vaccines prevent you from spreading the virus or just protect you from the disease?
Scientists don’t know yet – and uncertainty has big implications during vaccine launches.
Pfizer and Moderna, the companies that have so far developed US-authorized vaccines, say their vaccines are about 95% effective in preventing people with Covid symptoms. But there is still not enough evidence on whether vaccines also prevent infection and asymptomatic transmission.
Companies say research is underway to determine the answer. Without vaccines, research has suggested that asymptomatic Covid-induced coronavirus transmission is responsible for about a quarter of infections.
The result, experts say, is that precautionary measures such as wearing masks, social distancing and avoiding crowded spaces will be necessary until the country gets close to the herd’s immunity, where enough people are immune to a disease to spread it. unlikely. Some studies have estimated that about 75% to 80% of the US population must be immune to Covid-19 to achieve herd immunity, but this number is a moving target and could increase as new variants emerge.