Adverse Events Following One Dose of mRNA COVID-19 Vaccination Among US Nursing Home Residents With and Without a Previous SARS-CoV-2 Infection.
Barbara H Bardenheier, Stefan Gravenstein, Carolyn Blackman and 8 others
PMID 34534492WHAT IT FOUND
After first mRNA dose, nursing home residents with prior SARS-CoV-2 infection did not appear to have more adverse events than those without.
Deaths in 7 days were lower in prior infection groups, but this likely reflects who survived to be vaccinated.
Key findings
01For the rare events examined, differences between residents with and without previous infection were not significant after adjustment for multiple testing.
02After accounting for baseline differences, death in the 7 days after vaccination was lower among residents with previous symptomatic infection (risk ratio 0.61) and previous asymptomatic infection (risk ratio 0.51).
03Within 15 days, no cases of acute myocardial infarction, Bell's palsy, seizures, hemorrhagic stroke, ischemic stroke, or pulmonary embolism occurred among residents with previous SARS-CoV-2 infection.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
Residents with and without previous infection differed at baseline, including length of stay, age, sex, comorbidities, and cognition, so the groups were not comparable even after weighting. Only deaths and provider-coded diagnoses were used to identify events, and events were counted only if a provider coded them, so some events may have been missed or misclassified. Rare adverse events produced very small numbers, so estimates were imprecise. The lower mortality among residents with previous infection may be due to selective survival or immortal time bias, because only residents who survived infection and were well enough to be vaccinated were included. Adverse event comparisons were adjusted for multiple testing, but the authors say unobserved factors may still affect the results.
Declared interests
The supplied text does not include an author conflict-of-interest declaration; publication types list NIH and U.S. government research support.
The easy way to misread this
Do not read the lower 7-day mortality among residents with previous infection as evidence that vaccination reduced deaths. The authors say this finding may reflect selective survival or immortal time bias, because residents had to survive infection and remain well enough to be vaccinated.