The Pfizer coronavirus vaccine is 85 percent effective in reducing transmission after a single dose, a “groundbreaking” new Israeli study showed, lending credence to the notion the second shot can be delayed.
According to the study, conducted by a team at the Sheba Medical Center and based on more than 7,000 health care workers, the vaccine saw a drop of 85 percent of infections among symptomatic staff after a period of 15 to 28 days after the first shot was administered.
When taking into account asymptomatic cases, the number dropped to 75 percent.
Prof. Gili Regev-Yochay, Director of Sheba Medical Center’s Infectious Disease Epidemiology Unit, said the data was “very, very significant.”
“In real life we’re seeing excellent results,” she said. “What we see is really very high effectiveness just two to four weeks after the first shot.”
The reductions of infections “provide support of delaying the second dose in countries facing vaccine shortages and scarce resources, so as to allow higher population coverage with a single dose,” the study, which was published in the Lancet, said.
Prof. Arnon Afek, the Sheba hospital’s director-general, said: “This ground-breaking research supports the British government’s decision to begin inoculating its citizens with a single dose of the vaccine.”
However, the report added that it doesn’t prove any lasting impact of the first dose and as such, more follow-up is necessary “inform a second dose delay policy.”
In a separate study carried out by the Israeli Health Ministry and Pfizer, the vaccine was found to reduce transmission in asymptomatic cases by 89.4 percent and in syptomatic cases by 93.7 percent.