Authors believe broad trend applies to current, future waves

Vaccinated, boosted parents slash their kids’ COVID risk — pre-Omicron Israeli study

As most of world’s young kids not yet eligible, research shows kids living with 2 inoculated parents during Alpha outbreak had 72% fewer infections than unvaxxed parents’ offspring

Nathan Jeffay is The Times of Israel's health and science correspondent

An Israeli woman receives her dose of COVID-19 vaccine, at a Ministry of Health vaccine center at the Malcha mall in Jerusalem, on December 23, 2021. (Olivier Fitoussi/Flash90)
An Israeli woman receives her dose of COVID-19 vaccine, at a Ministry of Health vaccine center at the Malcha mall in Jerusalem, on December 23, 2021. (Olivier Fitoussi/Flash90)

An Israeli-led research team has found that parents massively reduce their kids’ chances of catching coronavirus by vaccinating themselves.

The research has major relevance for much of the world, where adult vaccines are available and shots for young children are not yet on offer, and many parents are wondering how to best protect their offspring.

In the peer-reviewed study, published in the journal “Science,” researchers found that during the outbreak of the Alpha variant in early 2021, Israeli kids who lived with two vaccinated parents had a 72 percent lower risk of infection than children who lived with unvaccinated parents. In families with one vaccinated parent, the risk reduction was 26%.

It is unclear how precisely those figures hold for the current Omicron wave or for future outbreaks, but the study’s authors believe that the broad trend identified still applies.

They emphasize that the sample size for the Alpha research was very large, some 155,000 households. The participants were members of the Clalit healthcare provider, which conducted the study in collaboration with researchers from Harvard University and Tel Aviv University.

“This study shows that vaccinating parents very much protects children who aren’t yet eligible for vaccines,” Dr. Noam Barda, one of the study’s authors, told The Times of Israel. “Actually, it shows that it’s probably the best thing we can do for kids, and the study is a call for parents who aren’t vaccinated or aren’t up to date with boosters to take action to protect their loved ones.”

Another author of the study, and a researcher at Harvard Medical School, Dr. Ben Reis, said: “Parents have a sacred duty to protect their children from harm. Especially in families where children are too young to be vaccinated, this study provides stark evidence of the importance of parents being vaccinated – protecting not only themselves, but their children as well.”

A health worker takes test samples from children in Jerusalem on August 11, 2021. (Olivier Fitoussi/Flash90)

Barda, a Clalit analyst and lecturer at Ben Gurion University, emphasized boosters because the second part of the study correlated infection levels among kids during the Delta wave of June to November 2021 with the take-up of the third shots, which were introduced during the wave.

After studying around 77,000 households, the researchers found that when one parent in a family had a booster shot, it lowered the risk of children being infected by 21%, compared to households where parents had just two shots. In families where two parents had boosters, the kids had a 58% lower infection risk than in families with double-vaccinated parents.

Prof. Ran Balicer, director of Clalit’s research arm and also a top coronavirus adviser to the Israeli government, said the lower infection levels are due to a combination of parents being more protected against getting infected, and transmitting infection less to people around them, if they catch the coronavirus.

“For the first time, we are able to quantify the indirect protection provided from vaccinated parents to unvaccinated children,” he said.

“We did this while highlighting the mechanism of the protection, that is partly mediated by lower infectiousness of vaccinated parents. Even if the parents have a breakthrough [infection], still they are less likely to transmit the disease to their unvaccinated children, compared to unvaccinated parents.”

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