JERUSALEM (Reuters) – Pfizer Inc’s first dose of COVID-19 vaccine is 85% effective, study of health workers at an Israeli hospital finds that may spark debate over the recommended two-dose schedule as governments try expand stocks.
The Sheba Medical Center findings are comparable to the overall efficacy of approximately 95% in a two-dose regimen 21 days apart before injection developed with BioNTech of Germany.
The Sheba study, which will be published in the medical journal The Lancet, comes a day after Canadian researchers suggested that, given the high level of protection from the first injection, the second dose of Pfizer should be delayed to increase the number of people being vaccinated .
Their study showed an efficacy of 92.6% after the first dose, based on an analysis of the documents submitted by the drug manufacturer from its late-phase human trials to the U.S. Food and Drug Administration in December.
The FDA said in December that data from those studies showed that the vaccine began to provide recipients with some protection before they received the second injection, but more data would be needed to assess the potential of a single-dose injection.
Pfizer has said alternative vaccine dosing regimens have not yet been evaluated and the decision rests with the health authorities.
Sheba said that among 7,214 hospital workers who received their first dose in January, there was an 85% reduction in symptomatic COVID-19 within 15 to 28 days. The overall reduction in infections, including asymptomatic cases detected by testing, was 75%.
Sheba epidemiologist Gili Regev-Yochay warned that the cohort studied in the hospital was “mostly young and healthy.”
Unlike Pfizer’s clinical trial, “we don’t have many (staff) over 65 here,” she told reporters. But she also noted that the Sheba trial took place during an increase in COVID-19 infections in Israel, flooding hospitals with new cases.
Pfizer declined to comment on the data, saying in a statement that it was doing its own analysis of “the actual effectiveness of the vaccine in various locations around the world, including Israel.” It hopes to use Israeli data to look at the vaccine’s potential to protect against COVID-19 due to emerging variants, the drugmaker said.
Written by Dan Williams; Editing by Jane Merriman