JERUSALEM (Reuters) – Pfizer’s COVID-19 vaccine significantly reduces the transmission of the virus, two Israeli studies have revealed, shedding light on one of the biggest questions in the global pandemic eradication effort.
Analysis of data from a study by the Israeli Ministry of Health and Pfizer Inc. found that the Pfizer vaccine developed with BioNTech in Germany reduces infection, including asymptomatic cases, by 89.4% and symptomatic cases by 93.7%.
The results of the pre-published study, which have not yet been evaluated by colleagues, but based on a national database that is one of the most advanced in the world, were first reported by Israeli news site Ynet late Thursday and were obtained by Reuters on Friday.
Pfizer declined to comment, and the Israeli Ministry of Health did not respond to a request for comment.
A separate study by Israel’s Sheba Medical Center, published in The Lancet on Friday, found that among 7,214 hospital staff who received the first dose in January, there was an 85% reduction in symptomatic COVID-19 during 15 to 28 days, with an overall reduction in infections, including asymptomatic cases detected by testing, of 75%.
More research is needed to draw a definitive conclusion, but studies are among the first to suggest that a vaccine could stop the spread of the new coronavirus and not just to prevent people from getting sick.
Michal Linial, a professor of molecular biology and bioinformatics at the Hebrew University of Jerusalem, said the findings are a big step toward answering one of the most important questions in the fight against the pandemic.
“Whether it’s a 75 or 90 percent reduction doesn’t matter – it’s a big drop in transmission,” Linial said. “It means that not only is the vaccinated person protected, but also the inoculation provides protection for the environment.”
The researchers said that an additional study on asymptomatic transmission in fully vaccinated people is needed because they are less likely to be tested for COVID-19.
Vaccine developers also said more research is needed on transmissibility. In December, BioNTech in Germany said it would take another three to six months to study.
“DYNAMIC VIRUS”
Leading the world in vaccine implementation, Israel’s universal medical services and advanced data capabilities have provided a nationwide database that can provide information on how effective vaccines are outside of controlled clinical trials.
The study of the Ministry of Health / Pfizer analyzed the data collected between January 17 and February 6, regarding the people who were completely vaccinated, after receiving the second Pfizer vaccine.
To date, more than 30%, or 2.8 million of Israel’s population of nine million, have received both doses.
Sheba’s study found that only the first dose of Pfizer vaccine was 85% effective, potentially fueling a debate over the recommended two-dose schedule.
Canadian researchers in a letter published this week suggested that the second dose of Pfizer be delayed, given the high level of protection from the first blow to increase the number of people vaccinated.
The US Food and Drug Administration said in December data from these studies showed that the vaccine began to provide some protection to recipients before receiving a second injection, but more data would be needed to assess the potential for a single dose.
Pfizer said alternative vaccine dosing regimens have not yet been evaluated and that the decision rested with health authorities.
Another warning is that the cohort studied at the hospital was “mostly young and healthy,” said epidemiologist Sheba Gili Regev-Yochay.
Unlike the Pfizer clinical trial, “we don’t have many (staff) here over the age of 65,” she told reporters. But he also said that the Sheba study took place during an increase in coronavirus infections in Israel, which flooded hospitals with new cases.
Pfizer declined to comment on the data, saying in a statement that it was conducting its own analysis of the “real-world effectiveness of the vaccine in several locations around the world, including Israel.”
The results of both studies were compared with the overall efficacy of approximately 95% in a two-dose regimen 21 days apart. Researchers from the Ministry of Health / Pfizer have found that the vaccine is effective against the British variant of coronavirus, which accounts for about 80% of confirmed cases in Israel.
Eran Kopel, an epidemiologist at Tel Aviv University, said the Sheba study was important, but focused on a hospital and a relatively small group of people, so “no clear epidemiological conclusions could be drawn from it.”
Health Ministry data was encouraging, he said, but additional research and periodic surveys are needed.
“Vaccinations are a very good tool, but this is not the end. This is a dynamic virus that has surprised the scientific world with the rapid pace of change and variety, “he said.
Additional reporting by Dan Williams to Jerusalem; Editing by Jane Merriman and Barbara Lewis