Research: Pfizer COVID vaccine efficacy wanes 27 days after dose 2 in teenagers

A brand new study finds waning Pfizer/BioNTech COVID-19 vaccine safety towards symptomatic an infection in Brazilian and Scottish teenagers beginning 27 days after the second dose amid the Delta and Omicron variant waves, however safety towards extreme sickness was nonetheless sturdy at 98 days in Brazil.

The research, printed yesterday in The Lancet Infectious Illnesses, analyzed nationwide information from 503,776 COVID-19 checks of two,948,538 adolescents aged 12 to 17 years from Sep 2, 2021, to Apr 19, 2022, in Brazil, and 127,168 checks of 404,673 adolescents from Aug 6, 2021, to Apr 19, 2022, in Scotland. Safety towards extreme sickness, outlined as hospitalization or loss of life inside 28 days, was estimated solely in Brazil owing to the small variety of such circumstances in Scotland.

The researchers estimated vaccine effectiveness (VE) towards symptomatic COVID-19 by evaluating the time elapsed because the first or second dose in adolescents who examined optimistic on polymerase chain response (PCR) checks in Scotland, or by PCR or antigen check in Brazil, and people who examined adverse (controls).

The interval was marked by the Omicron surge in each international locations, supplanting Delta in December 2021 in Scotland and January 2022 in Brazil. Vaccine rollout for this age-group started in August 2021 in Scotland and September 2021 in Brazil.

The research authors stated the research was the primary to make use of nationwide information to evaluate VE towards extreme COVID-19 outcomes over time amongst adolescents amid Omicron.

VE towards Omicron signs 5.9% at 98 days in Brazil

In Brazil, over the research interval, 176,002 (34.9%) COVID checks had been optimistic, and 327,774 (65.1%) had been adverse. Throughout Omicron, 355,066 checks had been recorded, with 150,291 (42.3%) optimistic, and 204,775 (57.7%) adverse. Amongst sufferers who had 150,291 Omicron-positive checks, 585 (0.4%) turned severely in poor health.

In Scotland, 60,574 COVID-19 checks had been optimistic (47.6%), and 66,616 had been adverse (52.4%) over the research interval. Of the 45,771 checks carried out throughout Omicron, 26,177 (57.2%) had been optimistic, and 19,954 (42.8%) had been adverse.

Estimated vaccine effectiveness (VE) peaked 14 to 27 days after dose two in each international locations in each the Delta and Omicron waves and was considerably decrease towards symptomatic COVID-19 throughout Omicron in Brazil (64.7%; 95% confidence interval [CI], 63.0% to 66.3%) and Scotland (82.6%; 95% CI, 80.6% to 84.5%) than amid Delta in Brazil (80.7%; 95% CI, 77.8% to 83.3%) and Scotland (92.8%; 95% CI, 85.7% to 96.4%).

Throughout Omicron, 27 days after the second vaccine dose, VE towards symptomatic an infection started to fall, plummeting to five.9% (95% CI, 2.2% to 9.4%) in Brazil and 50.6% (95% CI, 42.7% to 57.4%) in Scotland at 98 days or extra. Over the identical interval after dose two in Brazil, VE towards extreme an infection stayed above 80% at 28 days and was 82.7% (95% CI, 68.8% to 90.4%) at 98 days or extra.

“Two doses of vaccination with BNT162b2 [Pfizer] amongst adolescents are inadequate to maintain safety towards symptomatic illness; nonetheless, they do provide substantial safety towards severe COVID-19 outcomes for at the very least 3 months,” the researchers wrote. “Our findings help the significance of maximizing vaccination protection and the consideration of booster doses for adolescents, although additional analysis is required.”



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