Pfizer vaccine dates in Israel give clues about herd immunity: scientists


Pfizer and BioNTech said they are working on a real-world analysis of data from Israel.

The vaccine against Pfizer Inc. and BioNTech SE Covid-19 appeared to prevent the vast majority of recipients in Israel from becoming infected, providing the first real-world indication that immunization will inhibit the transmission of the coronavirus.

The vaccine, introduced in a national vaccination program that began December 20, was 89.4% effective at preventing laboratory-confirmed, according to a copy of a draft publication posted on Twitter and verified by a trusted person Infections do the job. The companies worked with the Israeli Ministry of Health on the preliminary observational analysis, which was not peer-reviewed. Some scientists have denied its accuracy.

The results, which were also published in Der Spiegel, are the latest in a series of positive data from Israel, which has administered more Covid vaccines per capita than anywhere else in the world. Almost half of the population has received at least one dose of vaccine. Separately, Israeli authorities said Saturday that Pfizer-BioNTech’s shot was 99% effective in preventing deaths from the virus.


A nurse delivers the Pfizer BioNTech vaccine at McLeod Health Clarendon Hospital in South Carolina.

If confirmed, the early results on laboratory-tested infections are encouraging as they suggest that the vaccine may also prevent asymptomatic carriers from spreading the virus that causes Covid-19. This is not clear as the clinical trials testing the safety and effectiveness of vaccines focused on their ability to stop symptomatic infections.

Herd immunity

“This is the data we need to see in order to gauge the potential for herd immunity to be achieved with vaccines,” Raina MacIntyre, professor of biosecurity at the University of New South Wales in Sydney, said in an email on Monday. “However, we need to be able to see the data published in a peer-reviewed journal and examine the data in detail.”

Pfizer and BioNTech said they are working on a real-world analysis of data from Israel that will be shared once complete. Speakers declined to comment on unpublished data.

The study was not designed to accurately measure a reduction in SARS-CoV-2 transmission because national test data were used without considering differences in test rates between vaccinated and unvaccinated people, said Zoe McLaren, associate professor at the school of Public Policy at the University of Maryland Baltimore County.

“The main result outperforms the reduction in transmission from the Pfizer vaccine,” McLaren said in an email.


The study compares the number of reported cases between those who have been fully vaccinated and those who have not, but vaccinated people are less likely to be tested, so the data under counts cases, especially asymptomatic cases, in this group, she said.

“Need More Evidence”

“That means the actual reduction in transmission is less than the 89.4% estimate,” said McLaren. “How much lower? We need more evidence to be sure. But I assume that once we address the biases, we’ll still find that this vaccine reduces transmission. And that would be very good news.” “

About 80% of the SARS-CoV-2 cases in Israel during the study period from January 17 to February 6 were caused by the more communicable strain, which was first identified in the UK. The variant designated as B.1.1.7 occurred, led to infections and led to a third lock on January 8th.

As of February 6, about 27% of people aged 15 and over in Israel were fully vaccinated, with Pfizer-BioNTech shooting down the only vaccine available in the country. People were considered fully vaccinated and included in the analysis if the data collected was more than seven days after receiving their second dose.

Based on the infectivity of SARS-CoV-2, a vaccine that is 89% effective at preventing infection is likely to be effective in eliminating Covid-19 in a population where vaccination rates are high, said Helen Petousis-Harris, a vaccinologist at the University of Auckland.

The elimination of Covid-19 will reveal potential “reservoirs” of SARS-CoV-2 in animals, genetic alterations to the virus that could allow it to escape vaccine-induced immunity, and the ability to transmit around the world to stop depending, said Petousis-Harris, co-head of the Global Vaccine Data Network, a multinational group that collaborates on vaccine safety studies.


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