Overview
- Four weeks after vaccination, effectiveness was 44.7% against infection, 45.1% against emergency‑department visits, and 57.5% against hospitalization or death.
- Effectiveness declined to 35.5%, 42.9%, and 49.7% at 10 weeks, and to 16.7%, 39.1%, and 34.0% at 20 weeks for the same outcomes.
- Comparisons across Omicron subvariants showed similar levels of protection in the real‑world analysis.
- The findings were published October 27 in JAMA Internal Medicine by a team led by UNC biostatistician Danyu Lin with collaborators in Nebraska and Canada.
- The authors advise annual vaccination for people at elevated risk; CDC guidance maintains access for most adults 65 and older and for younger adults with qualifying conditions, with North Carolina pharmacies offering shots without a prescription for eligible individuals.