A new US study says that vaccines may prevent transmission of the coronavirus, which has been a central question about the inoculations.
The Mayo Clinic, in a study of 31,000 people in four US states who received at least one vaccine shot, found the inoculations were around 83% effective at preventing infections 36 days after the first shot.
For people who got both doses, the figure climbed to 89%.
Fifteen days after the first shot, protection against infection was 75%, said the study, which has not been peer-reviewed.
The study covered people who had received the Moderna or Pfizer vaccines.
Vaccines have been found to be highly effective at reducing symptomatic COVID-19 and mortality, but there is a dearth of data on whether they prevent transmission and can stop the virus from circulating within a population.
The question is crucial because most of the population in the US and worldwide remains unvaccinated and other groups, mainly children, are ineligible for the shots.