Using county COVID-19 positivity rates to decide how often to test nursing home staff members will lead to missed asymptomatic infections, a statewide study finds.  

The Centers for Medicare & Medicaid Services requires that the frequency for testing staff members be based on community infection positivity rates. Under the agency’s guidance, worker testing should increase from monthly to weekly when the surrounding county’s positivity rate is between 5% to 10%, and to twice weekly when positivity is above 10%.

Yet when almost 60,000 nursing home staff members in Indiana were tested for active SARS-CoV-2 infection, there was no threshold of community rates that predicted positivity. This was true for both county positivity rate or cases per 10,000 population, investigators reported.

“Even in areas with low levels of COVID-19 community activity … facilities in those areas still had infected staff,” study lead Kathleen Unroe, M.D., MHA, told McKnight’s.

Providers should consider whether to test more frequently than the recommended intervals to better disrupt staff-to-resident transmission and prevent facility outbreaks, said Unroe, a practicing geriatrician and researcher with the Indiana University Center for Aging Research at the Regenstrief Institute. 

“If the goal is to identify all asymptomatic SARS-CoV-2 infected nursing home staff, comprehensive repeat testing may be needed regardless of community level activity,” she and her colleagues wrote.

“[A]lthough there is a correlation with the number of infected staff and community COVID-19 activity, it is not optimal to use this as a guide for SARS-CoV-2 staff testing frequency,” researcher Justin Blackburn, Ph.D., of Indiana University concurred.

The findings are particularly important in light of new, widespread infection control strategies being implemented, such as point-of-care testing, the researchers added.

“We are still learning how best to utilize antigen and PCR testing,” Unroe said. To identify any possible asymptomatic positive staff, “we encourage frequent testing across the board. Particularly as capacity for testing picks up as it needs to, the CMS guidance could be considered a floor threshold.”

Beyond test frequency, results turnaround time is a critical aspect of accurate and useful testing, Unroe added. In fact, another study has found that only a “small fraction” of skilled nursing facilities receive COVID-19 test results back in less than a day, McKnight’s reported Monday.

Further data on the results of all-staff testing efforts are needed to help guide policy and protect high risk nursing home residents and staff, the current study’s authors concluded.

Full findings have been accepted for publication by JAMDA and can be accessed as a pre-publication proof.