The Covid-19 vaccine developed by Pfizer and BionNTech could protect against infection as well as preventing people from getting sick, according to an unpublished study, in what could boost the drug's potential as a tool for fighting the pandemic.
So far, clinical studies have only shown that the drug effectively prevents people from developing symptoms of illness, in 95% of cases, but it remains unclear whether vaccinated people could still catch the virus and therefore pass it on to others.
The vaccine is "highly effective" in preventing coronavirus infections, says a draft of the study, conducted by the German vaccine developer and its US partner together with the Israeli Health Ministry.
Analysing data from tens of thousands of positive coronavirus tests, the study found that the proportion of people with full vaccination coverage who tested positive for the virus within a given period was far lower than among those who had not been vaccinated.
The study authors wrote of an efficacy rate of 89.4%.
However, the document adds that the effectiveness in terms of preventing infection could be overestimated as a result of the methods of this particular study.
The draft was leaked to journalists at the Israeli news website ynet and has not been officially published, neither as a so-called pre-print nor in a peer-reviewed scientific journal.
BioNTech would not comment on the document on Sunday, nor would the Israeli Health Ministry.
The study is based on Israeli health data regarding vaccinated and unvaccinated people.