Home / News / World /  First dose of Pfizer's Covid-19 vaccine 85% effective: Study

Pfizer Inc's Covid-19 vaccine is 85% effective after the first shot, a study of healthcare workers at an Israeli hospital has found.

The Sheba Medical Center's said that among 7,214 hospital staff who received their first dose in January, there was an 85% reduction in symptomatic Covid-19 within 15 to 28 days. The overall reduction of infections, including asymptomatic cases detected by testing, was 75%.

Also Read | Turnout modest for second covid shot

However, Sheba epidemiologist Gili Regev-Yochay cautioned that the cohort studied at the hospital were "mostly young and healthy".

Unlike with Pfizer's clinical trial, "we don't have many (staff) here aged over 65," she told reporters. But she also noted that the Sheba study took place during a surge in Covid-19 infections in Israel, which flooded hospitals with new cases.

The findings compare with the overall efficacy of around 95% in a two-dose regimen 21 days apart for the vaccine.

This may lead to a debate over the recommended two-dose schedule as Canadian researchers had earlier suggested that the second Pfizer dose be delayed given the high level of protection from the first shot developed with Germany's BioNTech.

Their research showed the efficacy of 92.6% after the first dose, based on an analysis of the documents submitted by the drugmaker from its late-stage human trials to the US Food and Drug Administration in December.

The FDA said in December data from those trials showed that the vaccine began conferring some protection to recipients before they received the second shot, but more data would be needed to assess the potential of a single-dose shot.

Pfizer declined to comment on the data, saying in a statement it was doing its own analysis of "the vaccine’s real-world effectiveness in several locations worldwide, including Israel, reported Reuters.

It hopes to use Israeli data to look at the potential of the vaccine to protect against Covid-19 arising from emerging variants, the drugmaker said.

Vaccination in Israel

Israel has rolled out the fastest Covid-19 vaccination campaign in the world, inoculating more than 42% of its population since late December.

The small country—with roughly nine million people, about the same as New York City—now aims to inoculate the majority of its population by March.

Against South African variant

A top Pfizer Inc scientist said on Thursday that the company is in intensive discussions with regulators to test a booster shot version of its coronavirus vaccine specifically targeted for a highly contagious variant that is spreading widely in South Africa and elsewhere.

Phil Dormitzer, one of Pfizer's top viral vaccine scientists, said the current vaccine is highly likely to still protect against the concerning variant first discovered in South Africa.

A laboratory study released on Wednesday suggested that the South African variant of the coronavirus may reduce protective antibodies elicited by the Pfizer/BioNTech vaccine by two-thirds, but it is not clear how much that reduces the shot's effectiveness against the variant.

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