Experts who have been tracking the effectiveness of the Pfizer/BioNTech vaccine have found that the risk of Covid infection increases the longer it is since people had a second dose.
The study backs up the need for booster doses to prevent people suffering breakthrough infections as immunity wanes, according to the team, who published their findings in the British Medical Journal (BMJ).
Experts from the Research Institute of Leumit Health Services in Israel found a gradual increase in the risk of Covid-19 infection from 90 days after people received a second dose of the Pfizer/BioNTech vaccine.
Israel was one of the first countries to roll out a large scale Covid-19 vaccination campaign in December 2020, but has been battling a resurgence