Mass testing in LTCFs identified asymptomatic COVID-19 infections
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Mass testing prompted by COVID-19 outbreaks at four long-term care facilities in San Francisco revealed high rates of asymptomatic infections among residents and workers, according to data published in Clinical Infectious Diseases.
In San Francisco, COVID-19 surveillance in skilled nursing facilities has been ongoing since early March, said Janice K. Louie, MD, MPH, of the San Francisco Department of Public Health and the University of California, San Francisco.
“As part of active surveillance, we called our nursing home partners daily to ask about residents or health care workers with new symptoms like fever, cough, shortness of breath or other nonspecific symptoms that could be related to COVID-19, and then assisted with getting testing done at our public health laboratory,” Louie told Healio.
“In late March, we confirmed by laboratory testing several new cases in these nursing homes, with some residents requiring hospitalization,” Louie said. “This was at the same time that reports of rapid transmission of COVID-19 in nursing homes, including [those] due to asymptomatic infection, began emerging.”
Mass testing all residents and health care workers began as a way to better characterize and respond to the outbreaks, according to Louie.
“Being able to identify those residents and health care workers who were infected but asymptomatic helped us to control the outbreaks by cohorting the infected from noninfected residents in the nursing homes and having the infected health care workers stay home in isolation, monitor their own symptoms and see their physicians if they felt worse, and also advise their close contacts, household members and families to monitor for symptoms and consider getting tested,” she said.
Louie and colleagues assessed the results of the surveillance, response and control measures to prevent COVID-19 transmission in four long-term care facilities (LTCFs) in San Francisco.
According to their report, from March 30 through April 30, the San Francisco Department of Public Health investigated and responded to four outbreaks in these LTCFs, which housed residents in shared double or triple rooms.
Among the 431 people who were tested as part of the outbreak investigation, 214 (49.7%) were positive for COVID-19, including 128 (59.8%) who had symptoms and 86 (40.2%) who were asymptomatic. According to the study, of the 128 symptomatic infections, 50 (39.1%) were among health care workers and 78 (60.9%) were among residents. The investigation found that 22 (28.2%) residents required hospitalization and 12 (15.4%) hospitalized residents died, whereas no symptomatic health care workers required hospitalization or died.
Expanded testing identified an additional 303 asymptomatic people, including 147 (48.5%) health care workers and 156 (51.5%) residents. Of these, the investigation revealed that 86 (28.4%) were positive for COVID-19, including 23 (26.7%) health care workers and 63 (73.3%) residents, Louie and colleagues reported.
Further investigation identified four health care workers as the likely sources of transmission in each facility, including three who reported working while symptomatic, according to the report.
“Persons over 65 years in LTCFs are our most vulnerable population at risk for dying due to COVID-19, and we need to stay alert and do everything we can to protect them. We are all dealing with a new world with this novel virus,” Louie said. “Asymptomatic infection and lack of immunity in the population has led us to develop new strategies to protect our elderly at a level we have never had to address before, even in the worst influenza seasons.”
According to Louie, so far, the strategies seem to be working.
“The new normal should be continued regular mass testing in skilled nursing facilities, practicing universal masking and other infection control measures, and ongoing clinical vigilance for anyone with new symptoms with rapid testing for COVID-19 when indicated,” Louie said.
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