One dose of the Pfizer/BioNTech vaccine gives people about 90% protection from Covid by 21 days, according to an analysis of Israel’s mass vaccination programme.
The data analysis, carried out by researchers from the University of East Anglia with UK government funding, runs counter to an earlier study from Israel which suggested that one dose may not give adequate protection.
Prof Nachman Ash, in charge of the Israeli vaccination effort, said last month that a single dose appeared “less effective than we had thought”, and was also lower than Pfizer had suggested. Pfizer had said efficacy was 52% after a single dose.
But Prof Paul Hunter and Dr Julii Brainard say their reanalysis of the data, which has not been peer-reviewed, shows high protection just before the second dose was given at 21 days. However, they warn that the risk of infection doubled in the first eight days after vaccination – possibly because people became less cautious.
