JERUSALEM (Reuters) – Pfizer’s COVID-19 vaccine greatly reduces transmission of the virus, two Israeli studies have found, shedding light on one of the biggest issues in the global effort to end the pandemic.
Data analysis in a study by the Israeli Ministry of Health and Pfizer Inc found that the Pfizer vaccine developed with BioNTech in Germany reduces infection, including in asymptomatic cases, by 89.4% and in symptomatic cases by 93.7% %.
The results of the pre-published study, not yet peer-reviewed, but based on a national database that is one of the most advanced in the world, were first reported by Israeli news site Ynet on Thursday night and were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 from Israel’s Sheba Medical Center published on Friday in the medical journal The Lancet found that among 7,214 hospital employees who received their first dose in January, there was an 85% reduction in symptomatic COVID-19 in 15 to 28 days with a general reduction in infections, including asymptomatic cases detected by testing, of 75%.
More research is needed to reach a definitive conclusion, but studies are among the first to suggest that a vaccine can prevent the spread of the new coronavirus and not just prevent people from getting sick.
Michal Linial, professor of molecular biology and bioinformatics at the Hebrew University of Jerusalem, said the findings were a big step in answering one of the most important questions in combating the pandemic.
“It doesn’t matter if it’s a 75 or 90 percent reduction – it’s a huge drop in transmission,” said Linial. “This means that not only is the vaccinated individual protected, inoculation also offers protection to his surroundings.”
The researchers said more studies are needed on asymptomatic transmission among fully vaccinated people because they are less likely to be tested for COVID-19.
Vaccine developers also said that more research on transmissibility is needed. In December, Germany’s BioNTech said it would take three to six months more studies.
‘DYNAMIC VIRUS’
Leading the world in its implementation of vaccination, Israel’s universal health and advanced data resources have provided a national database that can provide insights into the effectiveness of vaccines outside of controlled clinical trials.
The Ministry of Health / Pfizer study analyzed data collected between January 17 and February 6, looking at individuals who had been fully vaccinated after receiving the second injection from Pfizer.
To date, more than 30%, or 2.8 million of Israel’s nine million population, have received both doses.
Sheba’s study found that only the first dose of the 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 should be delayed due to the high level of protection from the first injection to increase the number of people vaccinated.
The Food and Drug Administration said in December that data from these tests showed that the vaccine started to provide some protection to recipients before receiving the second injection, but more data would be needed to assess the potential for a single dose.
Pfizer said alternative vaccine dosing regimes still need to be evaluated and that the decision rests with health officials.
Another caveat 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 (employees) here over 65,” she told reporters. But she also said that Sheba’s study occurred during an outbreak of coronavirus infections in Israel, which flooded hospitals with new cases.
Pfizer declined to comment on the data, saying in a statement that it was doing its own analysis of “vaccine effectiveness in the real world in various locations around the world, including Israel”.
The results of both studies were compared with the overall efficacy of about 95% on a two-dose regimen 21 days apart. Researchers at the Ministry of Health / Pfizer found that the vaccine is effective against the British coronavirus variant, which represents about 80% of Israel’s confirmed cases.
Eran Kopel, an epidemiologist at the University of Tel Aviv, said that Sheba’s study was important, but that it focused on a hospital and a relatively small group of people, so “you couldn’t draw clear epidemiological conclusions from it.”
The Ministry of Health data is encouraging, he said, but more research and regular surveys are needed.
“Vaccines are a very good tool, but this is hardly the end. This is a dynamic virus that surprised the scientific world with its fast pace of change and variety, ”he said.
Additional reporting by Dan Williams in Jerusalem; Editing by Jane Merriman and Barbara Lewis