The first dose of the Pfizer-BioNTech vaccination is 85% effective against coronavirus infection between two and four weeks after inoculation, according to a study published in the Lancet medical journal.
The survey was carried out on healthcare workers at the largest hospital in Israel, which on 19 December launched a mass vaccination campaign regarded as the world's fastest.
Israeli studies have found the Pfizer-BioNTech vaccine to be 95% effective one week after a second jab, while the Lancet report focused on more than 9,000 medical staff at Sheba hospital near Tel Aviv.
Some 7,000 of them received the first dose and the rest were not inoculated. From the group, 170 were diagnosed with Covid-19 after tests carried out only on those