Efficacy of Pfizer/BioNTech coronavirus vaccine drops to 84pc after 6 months

The efficacy of the Pfizer/BioNTech coronavirus vaccine fell from 96% to 84% after six months, a new preprint report by medRxiv showed on Wednesday.

Advertisment

1/38

2/38

3/38

4/38

5/38

6/38

7/38

8/38

9/38

10/38

11/38

12/38

13/38

14/38

15/38

16/38

17/38

18/38

19/38

20/38

21/38

22/38

23/38

24/38

25/38

26/38

27/38

28/38

29/38

30/38

31/38

32/38

33/38

34/38

35/38

36/38

37/38

38/38

"Efficacy peaked at 96.2 percent during the interval from 7 days to <2 months post-dose 2, and declined gradually to 83.7 percent from 4 months post-dose 2 to the data cut-off, an average decline of ~6 percent every 2 months," the report said.

Ongoing follow-up is needed to understand the persistence of the vaccine effect over time, it added.

According to data that has not been reviewed, the vaccine was initially 91% effective at preventing COVID-19 over the course of six months.

The US health-oriented news outlet Stat suggested that if the vaccine efficacy keeps declining at the rate described in the study, it will end up being less than 50% within 18 months from the date of vaccination and so a third dose would be required.