Universal Testing of Nursing Homes Residents Identifies Asymptomatic Cases

July 15, 2020

When universal testing was implemented, 40% of the tested residents were positive for SARS-CoV-2.

Universal COVID-19 testing of residents of 11 Maryland long-term care facilities found that close to 40% of the residents were infected with the SARS-CoV-2 virus, according ot a research report published in JAMA Internal Medicine.

The authors, led by Benjamin F. Bigelow, at Johns Hopkins, say their results show that symptom-based testing is not adequate to identify cases in long-term facilities and inform efforts to control or prevent outbreaks.

Testing only of residents with symptoms identified 153 cases within 20 days of thge detection of an index case in the nursing homes, they report.

When the remaining 893 residents were tested, 354 (39.6%) were postive for the SARS-CoV-2 virus that causes COVID-19.

The total number of positive cases in the nursing home was 507, and more than half (55.4%) were asymptomatic.

The testing used the standard nasopharyngeal swab sample and then reverse-transcriptase PCR test to see if the sample showed evidence of infection.

Follow-up universal testing of 426 residents at seven of the nursing homes identified 177 cases and of those, 154 (87%) were asymptomatic. Twenty of the peope who were asymptomatic when they tested positive were eventually hospitalized, and 7 (4.6%) died within 14 days of testing.