Pfizer COVID vaccine shown highly protective in teens against DeltaThe estimated effectiveness of the Pfizer/BioNTech COVID-19 vaccine against infection in US adolescents was 91%, with 93% protection against symptomatic illness and 85% against asymptomatic disease amid the Delta SARS-CoV-2 surge in Connecticut, finds a study published yesterday in JAMA Network Open.The retrospective case-control study, by Yale School of Medicine researchers, involved the electronic medical records of 542 adolescents aged 12 to 18 years old tested for COVID-19 within 4 months of the Pfizer vaccine rollout for teens.
The study spanned the Delta SARS-CoV-2 variant surge, from Jun 1 to Aug 15, 2021, when the strain made up 92% of infections in Connecticut.Among the 542 adolescents, 186 were diagnosed as having COVID-19, and 356 were matched uninfected controls.
A total of 134 adolescents (25%) had received their second vaccine dose at least 14 days before (10 COVID-19 patients [5%], 124 controls [35%]).Median participant age was 14 years, 48% were girls, 15% were Black, 15% were Hispanic, and 55% were White.
Median time between vaccination and COVID-19 testing was 62 days. The proportions of infected and control participants were different in terms of asymptomatic cases (39% vs 91%), uninsured status (17% vs 10%), Hispanic ethnicity (20% vs 13%), and known exposure to an infected person (73% vs 82%).