A third dose of Pfizer /BioNTech's Covid-19 vaccine was found to be 86 per cent effective in people aged over 60, an Israeli healthcare provider said, citing initial results from a study of thousands of members.

Israeli HMO Maccabi, which covers around a quarter of the country's 9.3 million population, compared results from 149,144 people aged over 60 who received their third dose at least a week ago against those from 675,630 more who had received only two doses, between January and February, according to a Reuters report.

Some 37 people tested positive for coronavirus after their third jab, compared with 1,064 positive cases among those who had received only two doses, Maccabi said in a statement. The comparison groups had similar demographic profiles, it added.