Study shows Pfizer vaccine efficacy for Covid-19 infection in children and adolescents during Omicron is very weak.

https://jamanetwork.com/journals/jama/fullarticle/2792524 

Full pdf file available in the article.

Findings:  In a test-negative, case-control study conducted from December 2021 to February 2022 during Omicron variant predominance that included 121 952 tests from sites across the US, estimated vaccine effectiveness against symptomatic infection: 

Children 5 to 11 years of age 

60.1% 2 to 4 weeks after dose 2 

28.9% during month 2 after dose 2. 

Adolescents 12 to 15 years of age

59.5% 2 to 4 weeks after dose 2 

16.6% during month 2 after dose 2 

71.1%. during 2 to 6.5 weeks after dose 3 (booster)