Pfizer/BioNTech say data suggests vaccine 94% effective in preventing asymptomatic infection

Michael Erman and Maayan Lubell
·2-min read

By Michael Erman and Maayan Lubell

NEW YORK/JERUSALEM (Reuters) - Pfizer Inc and BioNTech SE said on Thursday that real-world data from Israel suggests their COVID-19 vaccine is 94% effective in preventing asymptomatic infections, suggesting it could significantly reduce virus transmission.

The companies also said the latest analysis of the Israeli data shows the vaccine was 97% effective in preventing symptomatic disease, severe disease and death. That is in line with the 95% efficacy reported in the vaccine's late-stage clinical trial in December.

Israel's Health Ministry, which is working with the healthcare providers administering the vaccine, said in an emailed statement that the data was developed from the ministry's tracking of morbidity.

Israel’s Health Ministry previously found that the Pfizer/BioNTech vaccine reduces infection, including in asymptomatic cases, by 89.4% and in symptomatic cases by 93.7%. That was from data collected from Jan. 17 to Feb. 6.

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Pfizer Chief Executive Albert Bourla said the data was important for society because it means fewer people are passing on the virus to others without knowing it. The company plans to publish the data in a peer reviewed journal, he said.

The analysis also shows real-world evidence of the vaccine's effectiveness against a highly infectious variant of COVID-19 first discovered in Britain, known as B.1.1.7. More than 80% of the tested specimens were that variant.

There was no evaluation of its effectiveness against the virus variant first discovered in South African known as B.1.351 due to the limited number of infections with that variant in Israel.

As of Wednesday, around 55% of Israel's 9 million population had been given at least one dose of the Pfizer/BioNTech COVID-19 vaccine, according to Health Ministry data, and 43% have received both doses.

According to the analysis of data collected from Jan. 17 to March 6, unvaccinated individuals were 44 times more likely to develop symptomatic COVID-19 and 29 times more likely to die from the illness.

In a previous unpublished study by the health ministry and Pfizer, Israeli researchers said further study was needed on asymptomatic transmission among fully vaccinated people because they are less likely in Israel to be tested for COVID-19.

Since the mid-January peak, Israel has seen 71% fewer COVID-19 deaths, 55% fewer cases, 45% fewer new critically ill patients and 40% fewer critically ill patients in hospitals, according to Eran Segal, a data scientist at the Weizmann Institute of Science.

On Wednesday, 2,802 Israelis tested positive, or 2.9%, from nearly 99,000 tests.

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(Reporting by Michael Erman in New York and Maayan Lubell in Jerusalem; Additional reporting by Steven Scheer and Ari Rabinovitch; Editing by Toby Chopra, Alexandra Hudson and Bill Berkrot)