Universal Testing Catches Hundreds of Asymptomatic COVID-19 Cases in 11 Nursing Facilities

Another study has shown the benefits of universal COVID-19 testing at nursing homes, especially when compared to a symptom-based strategy — while also revealing how long even the most vulnerable residents can remain asymptomatic after a positive test.

Universal testing caught 354 positives that symptom-based strategies missed at 11 facilities across Maryland, a new research letter published Tuesday in JAMA Internal Medicine determined.

Among those same 11 facilities, testing only symptomatic residents resulted in 153 confirmed positives within 20 days of the first case. Of the 893 who received subsequent universal tests, 354 were found positive for the virus, bringing the total number of cases to 507. More than half of those, or 281, had no symptoms, according to the letter.


The team, led by researchers from the Johns Hopkins University School of Medicine in Baltimore, also performed a follow-up analysis at seven of the 11 properties two weeks after the first round. A full 87%, or 154 of the 177 positives patients discovered during the universal testing round, remained alive and asymptomatic 14 days later. Twenty were in the hospital, while seven had died.

Of the 23 follow-ups on patients who had symptoms at the time they were initially tested, four were in the hospital and two were dead two weeks later.

The Johns Hopkins team concluded that the 11-building study illustrates the need for additional testing resources at long-term care facilities during the novel coronavirus pandemic.


“These results underscore the importance of universal testing because symptom-based approaches may miss a substantial number of cases,” the team concluded. “Unrecognized asymptomatic cases among residents could perpetuate transmission within facilities.”

The letter also joins a growing body of research showing that asymptomatic spread of the disease plays a major role in outbreaks.