Resident Factors Associated With Breakthrough SARS-CoV-2 Infections

Area of Science:

• Gerontology
• Infectious Diseases
• Vaccinology

Background:

• Messenger RNA (mRNA) COVID-19 vaccines demonstrated high efficacy, but breakthrough infections (BTIs) can occur in vaccinated individuals.
• Nursing home residents are a vulnerable population with unique risks for severe COVID-19 outcomes.

Purpose of the Study:

• To determine the incidence of BTIs and severe illness among nursing home residents following two mRNA vaccine doses.
• To identify resident characteristics associated with an increased risk of BTIs and severe outcomes.

Main Methods:

• Retrospective cohort study of 23,172 nursing home residents vaccinated by March 31, 2021.
• Analysis of electronic health records and Minimum Data Set assessments to identify BTIs and severe illness (hospitalization/death within 30 days).
• Modified Poisson regression used to estimate incidence rate ratios for BTI, adjusting for facility-level factors.

Main Results:

• The incidence of COVID-19 BTI was 5% (1173/23,172 residents) over a mean follow-up of 250 days.
• Among residents with BTI, 8.6% experienced hospitalization or death within 30 days.
• Factors associated with severe illness included advanced age (≥85 years), bowel incontinence, coronary artery disease, chronic kidney disease, and schizophrenia.

Conclusions:

• Breakthrough infections and severe illness are uncommon in fully vaccinated nursing home residents.
• Older age and specific comorbidities significantly increase vulnerability to severe outcomes post-vaccination.
• These findings offer crucial prognostic data for nursing homes managing COVID-19 outbreaks amidst evolving public health policies.