Weekly screening of healthcare workers and other at-risk groups could have a significant impact on COVID-19 transmission, according to a World Health Organization-affiliated study.

Using a mathematical model, investigators found that testing healthcare and nursing home workers regularly — regardless of symptoms and using quick-result, point-of-care tests — would reduce their contribution to transmission by about 25%. This is on top of the reductions that would be expected by self-isolation in symptomatic individuals, the researchers said.

Healthcare workers have been disproportionately affected by COVID-19. In the United States, they account for at least 20% of COVID-19 cases, according to recent estimates. They are also a possible transmission source for the residents they care for.

“We find that testing is most useful when targeted at high-risk groups such as healthcare and [nursing home] staff,” said Professor Nicholas Grassly, an infectious disease specialist at Imperial College London. In contrast, widespread population testing would not be as effective when compared to contact-tracing and quarantine based on symptoms alone, he and his colleagues said. But it could allow for contacts to be released earlier from quarantine, they added.

Advocates have urged federal, local and state officials to provide immediate access to testing in eldercare facilities. “Without access to more testing, long term care providers are at a severe disadvantage in identifying … asymptomatic residents and staff,” said Mark Parkinson, president and CEO, American Health Care Association and National Center for Assisted Living in a statement last week.

The report was released by the WHO Collaborating Centre for Infectious Disease Modeling within the MRC Centre for Global Infectious Disease Analysis, J-IDEA, Imperial College London, in collaboration with the Vaccine Centre at the London School of Hygiene and Tropical Medicine.