COVID test being performed on a senior woman. Care provider is wearing full PPE.
The study’s results highlight the importance of facility-wide testing to identify and isolate cases.

More than 40% of nursing home residents with COVID-19 are asymptomatic, a multi-state study has found. Facility-wide testing was more successful in detecting these lurking infections than unit-only surveys, investigators discovered.

Study data were provided by Genesis HealthCare, which operates approximately 350 skilled nursing facilities nationwide. Investigators identified SARS-CoV-2 infections using de-identified electronic medical records and daily infection logs from March 16 to July 15. 

Overall, 41% of cases were asymptomatic, 19% were presymptomatic and 40% were symptomatic at presentation. The 173 facilities that conducted at least one facility-wide point prevalence survey identified slightly more cumulative rates of asymptomatic and presymptomatic infections than did facilities that tested only in specific units, reported Elizabeth White, Ph.D., APRN, of Brown University. 

The findings also add to growing evidence that location is an important predictor of nursing home outbreaks, White and colleagues said. Nursing homes located in counties with greater SARS-CoV-2 infection prevalence generally had higher combined counts of asymptomatic and presymptomatic cases than did nursing homes in counties with fewer infections, they wrote.

Asymptomatic people with COVID-19 have been found to be just as infectious as people who show symptoms. The current study’s results, therefore, underscore the importance of universal (facility-wide) testing to identify and isolate cases, White and colleagues concluded.

How residents were classified:

  • Asymptomatic: No symptoms from five days pretest to 14 days post-test
  • Presymptomatic: No symptoms in the five days before testing, but developed symptoms within 14 days thereafter
  • Symptomatic: New symptoms within five days before first positive test date

The study was published in JAMA Internal Medicine.