LAUSR

Key Points Question What is the estimated vaccine effectiveness (VE) and durability of BNT162b2 against infection with the Delta and Omicron variants of SARS-CoV-2 among 5- to 11-year-old children? Findings In this test-negative case-control study of 160 002 children who underwent polymerase chain reaction testing for SARS-CoV-2 at locations of a pharmacy chain during Delta- and Omicron-predominant periods, the overall VE of 2 doses of BNT162b2 was 85% against Delta and 20% against Omicron; protection from the 2-dose vaccine against Omicron waned after approximately 3 months and was similar across sublineages (BA.1, BA.2/BA.2.12.1, and BA.4/BA.5). Booster effectiveness was 55% against Omicron and 40% or more against BA.4/BA.5 at 3 or more months after receipt of the booster. Meaning This study suggests that 2 BNT162b2 doses provided limited protection against Omicron infection and that a booster dose restored and maintained protection for at least 3 months.