Pfizer effectiveness wanes in all age groups after a few months

Embargoed until: Publicly released: 2021-10-28 08:00

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Every age group is affected by the reduction in effectiveness of the Pfizer vaccine over time, according to a study out of Israel. During a surge of the Delta variant in July, the researchers compared the COVID-19 rates among those vaccinated when they were first eligible in early 2021 and those who were vaccinated a couple of months later. Across all ages 16 and over, those who were vaccinated earlier were infected about 1.6 times the rate of those vaccinated later, the researchers say. Additionally, they say the vaccine appeared to lose effectiveness at preventing severe disease too, with 60+ year-olds 1.8 times more likely to have severe disease if they were vaccinated early, and 40-59 year-olds 2.2 times more likely to be infected after early vaccination. The researchers say not enough people aged 16-39 had severe COVID-19 to get accurate data on waning immunity.