A pair of studies in yesterday in Science show the substantial benefit of COVID-19 vaccination to household contacts in Israel, including unvaccinated children.
But one of the studies highlighted waning protection over time.Two vaccinated parents better than 1 at curbing spreadA team led by Clalit Health Services researchers in Tel Aviv studied households consisting of two COVID-19–naïve parents and their unvaccinated children younger than 16 years from Jan 17 to Mar 28, 2021, and households with children younger than 11 years from Jul 11 to Sep 30, 2021.The early period was characterized by dominance of the Alpha (B117) variant and was before the availability of third COVID-19 vaccine doses.
During the latter period, the Delta (B1617.2) variant was dominant, and booster doses were extended to the entire population in August.In the early period, 400,733 unvaccinated children from 155,305 households participated.
Median age was 6 years. The later period involved 181,307 unvaccinated children from 76,621 households. Median age in that period was 5 years.The researchers also estimated the decline in risk of a vaccinated parent contracting COVID-19 (direct vaccine effectiveness), and the drop in risk that an infected vaccinated parent would then infect an unvaccinated child (household infectiousness).Parental vaccination (one parent) with two doses of the Pfizer/BioNTech COVID-19 vaccine was tied to a 26.0% (95% confidence interval [CI], 14.0% to 36.2%) lower risk to their children than no vaccination in the early period.