First shot of Pfizer-BioNTech Covid-19 vaccine offers significant protection

Just one dose of the Covid-19 vaccine developed by Pfizer-BioNtech is enough to provide a high degree of protection against the symptoms of the novel coronavirus, the results of an Israeli study concluded.

The results, which were published overnight in The Lancet medical journal, have prompted US authorities to mull spacing out more the time between the two doses of the shot given to each person - but there was a small caveat.

Symptomatic infections among more the more than 9,000 Israeli healthcare workers included in the study were cut by 85% over the 15 to 28 days following the first shot.

According to Arnon Afek, a co-author of the study and associate director general of the Sheba Medical Center: "Countries postponing second doses need to "understand the significance of the decision to give a single shot, and we show it carries quite substantial protection."

In the UK, officials allow the two doses to be delivered by as many as 12 weeks apart, against the 21 days allowed in the US and on the Continent.

That has allowed Israel and the UK to stretch their resources in order to protect as many people as possible more quickly, given the limited supply of vaccines.

Nonetheless, the Israeli researchers did caution that "Follow-up to assess long-term effectiveness of a single dose is needed to inform a second dose delay policy."