Coronavirus: How protection from Pfizer and Astrazeneca weakens over the months

  • Michelle Roberts
  • Health publisher, BBC News online

Woman being vaccinated against covid

Credit, Getty Images

Researchers say they are seeing a decrease in protection against Covid-19 infections in people who have received both doses of the vaccine.

One study, conducted in the UK with real-world data, looked at positive PCR test results between May and July 2021 in more than one million people who had received two doses of the Pfizer or AstraZeneca vaccine.

Protection after two doses of Pfizer decreased from 88% in one month to 74% in five to six months. In the case of AstraZeneca, the drop went from 77% to 67% in four to five months.

A reduction in protection is expected, according to experts.