Two studies done in Israel and published in the journal Science showed that during both the Alpha and Delta coronavirus waves, having fully vaccinated parents or fully vaccinated parents with a booster shot significantly decreased the chance of an unvaccinated child contracting the virus. It’s called a cocoon effect.
The first study found that during the part of the pandemic when the Alpha variant was in circulation, kids with two vaccinated parents had a 71.7% reduced risk of coming down with COVID. With the Delta, it was a 58.1% decreased risk.
“Parental vaccination confers substantial protection for unvaccinated children in the household,” said the researchers, who worked at Harvard University, Clalit Research Institute, Ben Gurion University, Tel Aviv University and Boston Children’s Hospital.
Another study looked at the rate of transmission among household contacts and bolstered the case for indirect protection from vaccines. The total vaccine effectiveness was estimated to be 91.8% within 10 to 90 days after vaccination and 61.1% more than three months after the second dose. There was evidence that protection waned beyond that time period, but the study did not take boosters into account.
The household is where many cases begin, the study suggests. Other studies have suggested the same. The risk of transmission from an infectious household member was 100 times as high as that of the average risk of infection from the community.
One expert said, “We’ve always known that kids are not the primary transmitters of this virus,” said Edwards, who was not affiliated with the new studies. “Adults have always been the primary transmitters of this virus, and so that’s why it’s always been incumbent on us, as adults, to be the ones to get vaccinated and to be the ones to wear the masks and to be the ones to be careful because we’re the ones that are primarily driving these outbreaks. We are the ones that can keep them safe.”
For decades we who provide healthcare for young children have been aware of this “cocoon” effect of vaccines. When a mother and father are immune to diphtheria and influenza, for example, their young baby is protected until they are old enough to get their own vaccines. Now the same cocoon effect appears to be working for COVID.
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