Also read: Coronavirus | WHO clears Pfizer-BioNTech COVID-19 vaccine for emergency useAround 1.2 million people were divided into equal groups of vaccinated and unvaccinated. Lead author Noam Barda, head of epidemiology and research at the Clalit Research Institute, told AFP the matching process was highly robust. The efficacy against symptomatic infections was 57% between 14-20 days after the first dose, but rose to 94% in seven days after the second dose -- very close to the 95% achieved during Phase 3 clinical trials. The study also found people who received their second dose had a 92% lower chance of getting any form of infection at all compared to those who were unvaccinated. That's because the participants weren't being systematically tested at regular intervals; rather, they were getting a test when they wanted one.

Source: The Hindu February 24, 2021 22:21 UTC