Observational study finds COVID-19 vaccines 94% effective against hospitalization in fully vaccinated older adults

An observational study assessed the real-world effectiveness of Pfizer-BioNTech and Moderna COVID-19 vaccines against hospitalization in U.S. adults aged 65 years or older. The analysis included hospitalized patients during January through March 2021, though the exact sample size was not reported. The study compared outcomes among vaccinated individuals but did not specify a formal comparator group.

The main finding was that full vaccination was associated with 94% effectiveness against COVID-19 hospitalization in this older adult population. For partially vaccinated individuals aged ≥65 years, the estimated effectiveness was 64%. The study reported these as effectiveness percentages; it did not provide the absolute numbers of cases, confidence intervals, or p-values for these estimates.

No safety, tolerability, or adverse event data were reported for this hospitalized cohort. Key limitations include the observational design, which can only show association, not prove causation. The lack of reported confidence intervals, absolute numbers, and details on the comparator group limits the precision and interpretability of the effectiveness estimates. The funding sources and potential conflicts of interest were also not reported.

For practice, this early real-world evidence from a high-risk population suggests mRNA COVID-19 vaccines were strongly associated with reduced hospitalization risk during the study period. However, clinicians should interpret the 94% and 64% figures cautiously due to the study's methodological limitations and the absence of statistical precision measures. The findings support vaccination in older adults but highlight the need for more complete data.