New data from Israel that had the fastest Covid-19 vaccine rollout in the world, provides real evidence that widespread vaccination against the coronavirus can protect even unvaccinated people.
The Israeli study, what was published in the journal Nature Medicine on Thursday, took advantage of the fact that until recently Israel vaccinated only people 16 years and older. For every 20 percentage points increase in the proportion of 16- to 50-year-olds who were vaccinated in a community, the researchers found that the proportion of unvaccinated under 16 years of age who tested positive for the virus decreased by half.
“Vaccination not only benefits the individual vaccinated but also the people around them,” said Roy Kishony, a biologist, physicist and data scientist who studies microbial evolution and disease at the Technion-Israel Institute of Technology. Dr. Kishony led the research with Dr. Tal Patalon, the head of a large health organization, KSM, the Maccabi Research and Innovation Center. The first authors of the paper are Oren Milman and Idan Yelin, researchers in Dr. Kishony.
Israel started vaccinating adults in December of last year. Within nine weeks, it had vaccinated nearly half of its population.
The researchers examined the anonymized electronic health records of members of Maccabi Healthcare Services, an Israeli H.M.O. They analyzed vaccination protocols and virus test results between December 6, 2020 and March 9, 2021. The records were from 177 different geographic areas with different vaccination rates and vaccine intake.
For each community, they calculated the proportion of adults between the ages of 16 and 50 who were vaccinated at different times. They also calculated the percentage of P.C.R. Tests done on children under the age of 16 who come back positive.
They found a clear connection: As more and more adults in a community were vaccinated, the proportion of children who tested positive for the virus fell as a result.
People who are vaccinated are significantly less likely to contract the virus. research also suggests that even if people who have been vaccinated do become infected with the virus, they may have a lower viral load, which reduces their infectiousness. As more and more people are vaccinated, the likelihood that unvaccinated people will encounter infected, contagious people is decreasing.
“The results are consistent with the fact that vaccinated people not only do not get sick themselves, but also do not transmit the virus to others,” said Dr. Kishony. “Such effects can be intensified over several infection cycles.”
in the another current paper, which has not yet been published in a scientific journal, Finnish researchers reported that after vaccination by health workers, even unvaccinated family members were less likely to be infected with the virus.