Thompson MG, Stenehjem E, Grannis S, et al. - In the United States, Covid-19 vaccines are reported to have great effectiveness against SARS-CoV-2 infection requiring hospitalization, ICU admission, or an emergency department or urgent care clinic visit. Populations that are disproportionately affected by SARS-CoV-2 infection also exhibited vaccine effectiveness.

• Assessed were a total of 41,552 admissions to 187 hospitals and 21,522 visits to 221 emergency departments or urgent care clinics for Covid-19–like illness in whom molecular testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was performed.

• Electronic health records and immunization registries were assessed for the patients’ vaccination status.

• Vaccine effectiveness was determined using a test-negative design by comparing the odds of a positive test for SARS-CoV-2 infection among vaccinated patients with those among unvaccinated patients.

• Full messenger RNA (mRNA) vaccination (≥ 14 days after the second dose) had effectiveness of 89% against laboratory-confirmed SARS-CoV-2 infection leading to hospitalization, 90% against infection leading to an ICU admission, and 91% against infection resulting in an emergency department or urgent care clinic visit.

• In case of complete vaccination, the BNT162b2 and mRNA-1273 vaccines had similar effectiveness with respect to a Covid-19–associated hospitalization or emergency department or urgent care clinic visit, ranging from 81% to 95% among adults 85 years of age or older, persons with chronic medical conditions, and Black or Hispanic adults.

• Ad26.COV2.S vaccine had effectiveness of 68% against laboratory-confirmed SARS-CoV-2 infection leading to hospitalization and 73% against infection leading to an emergency department or urgent care clinic visit.