Vaccinated adults help protect unvaccinated children, study finds
New data from Israel, which has experienced the world’s fastest deployment of the Covid-19 vaccine, provides concrete evidence that widespread vaccination against the coronavirus can also protect unvaccinated people.
The Israeli study, which was published Thursday in the journal Nature Medicine, took advantage of the fact that until recently Israel only vaccinated people 16 years of age or older. For every 20 percentage point increase in the share of vaccinated 16 to 50 year olds in a community, researchers found that the share of unvaccinated under 16s who tested positive for the virus halved.
âVaccination offers benefits not only to the individual vaccine, but also to the people around it,â said Roy Kishony, 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, who heads the KSM, the Maccabi Research and Innovation Center, in Israel. The first authors of the article are Oren Milman and Idan Yelin, researchers in Dr. Kishony’s laboratory.
Israel started vaccinating adults in December of last year. In nine weeks, he had vaccinated nearly half of his population.
Researchers examined the anonymized electronic health records of members of Maccabi Healthcare Services, an Israeli HMO. They analyzed vaccination records and virus test results between December 6, 2020 and March 9, 2021. The records came from 177 different geographic areas, which had different vaccination and vaccination rates.
For each community, they calculated the share of adults, aged 16 to 50, who were vaccinated at different times. They also calculated the fraction of PCR tests of children under 16 who came back positive.
They found a clear correlation: As more adults in a community got vaccinated, the share of children testing positive for the virus subsequently declined.
People who have been vaccinated are much less likely to be infected with the virus. Research also suggests that even when vaccinated people contract the virus, they may have a lower viral load, which reduces their infectivity. As a result, as more and more people get vaccinated, unvaccinated people are less likely to come across infected and contagious people.
“The results are consistent with the fact that vaccinees not only do not get sick on their own, but also do not pass the virus on to others,” said Dr Kishony. “Such effects can be amplified over several cycles of infections.”
In another recent article, which has not yet been published in a scientific journal, Finnish researchers reported that after vaccination of health workers, unvaccinated members of their household were also less likely to contract the virus.