Breakthrough COVID-19 Infection in Fully Vaccinated Nursing Home Residents

Nursing homes have been disproportionately impacted by COVID-19. Early in the pandemic, a third of the United States COVID-19 infections occurred in nursing homes. To date, 1.2 million nursing home residents have dies of COVID-19.

This high incidence rate led to nursing home residents being prioritized during the COVID-19 vaccine rollout; today, adults 65 years and older have the highest vaccination rate in the US. However, concerns remain about the frequency and severity of COVID-19 breakthrough infections among this vulnerable population.

A recent study, published in the Journal of Post-Acute and Long-Term Care Medicine (JAMDA), examined the incidence of and resident characteristics associated with breakthrough infections and severe illness among nursing home residents who had received 2 mRNA COVID-19 vaccines (1 complete primary vaccine series).

The investigators initially hypothesized that residents who were older and/or had advanced cognitive or functional impairment would have a higher risk of breakthrough infection and subsequent severe illness.

This retrospective cohort study included nursing home residents who completed a primary series of mRNA COVID-19 vaccination (Pfizer-BioNTech or Moderna) by March 31, 2021. To identify breakthrough infections and severe illness, the investigators utilized electronic health records and Minimum Data Set assessments from a multistate nursing home data consortium. “Severe illness” was a composite measure of hospitalization and/or death within 30 days of a confirmed COVID-19 breakthrough infection.

The study sample included 23172 residents from 984 nursing homes, all of whom were at least 14 days past their second mRNA COVID-19 vaccine dose. At 75.2% (n = 17418), most residents received Pfizer-BioNTech vaccines, while 24.5% (n = 5685) received Moderna and 0.3% (n = 69) had missing vaccine information. The median age of the residents was 78 years, and they were 61% female and 76% non-Hispanic White.

Of the 23172 nursing home residents, 5% (n = 1173) developed an incident breakthrough COVID-19 infection. Among residents who contracted a breakthrough COVID-19 infection, 8.6% were hospitalized or died within 30 days of their diagnosis. The average time of breakthrough infection was 250 days after vaccination.

Residents with breakthrough infection were typically older and non-Hispanic White. Additionally, residents with breakthrough infection were more likely to have chronic obstructive pulmonary disease, dementia, or osteoarthritis, but less likely to have functional impairment. Factors associated with severe or fatal breakthrough infection included age ≥ 85 years, bowel incontinence, coronary artery disease, chronic kidney disease, and schizophrenia.

The investigators concluded that 1 in 20 vaccinated nursing home residents (5%) had a COVID-19 breakthrough infection, significantly higher than the previously reported breakthrough infection rate of 0.3-0.8% among fully vaccinated nursing home residents. Notably, they wrote, the 8.6% hospitalization and/or death rate after breakthrough infection “is not much greater than mortality alone as reported in a separate study of newly admitted NH residents without COVID-19 infection (6.2%-6.9%).”