The protection provided by two doses of the Pfizer/BioNTech and the AstraZeneca coronavirus vaccines starts to wane within six months, new research suggests.
A reasonable worst-case scenario could see protection fall to below 50% for the elderly and healthcare workers by winter, an expert has said.
The Pfizer jab was 88% effective at preventing Covid-19 infection a month after the second dose. But after five to six months the protection decreased to 74%, suggesting protection fell 14 percentage points in four months, latest analysis from the Zoe Covid study indicates.
With the AstraZeneca vaccine, there was a protection against infection of 77% one month after the second dose. After four to five months protection decreased to 67%,