Zoe Berg, Photo Editor

In a Yale School of Public Health study, researchers found that rates of repeat positive tests among nursing home residents prior to widespread COVID-19 vaccine rollout were higher than in the general population and community-dwelling elderly.

The study was conducted by doctoral student Jillian Armstrong GRD ’23, Head of Health Care-Associated Infections for the state of Connecticut Vivian Leung and associate professor of epidemiology Sunil Parikh. The research indicated that approximately 2.6 percent of elderly nursing home residents tested positive after an initial positive test 90 days prior, and that 13 percent of those individuals died within a few weeks of the repeat positive test. 

This study is one of many conducted in collaboration between the YSPH and the Connecticut Department of Public Health and was published in The Lancet Regional Health — Americas on Aug. 21. Study authors also commented on the reasons behind the higher rates of repeat positive tests.

“Nearly 13% of [nursing home residents studied] died within a few weeks of the repeat positive test, suggesting that these repeat positive tests may be associated with severe outcomes,” Parikh wrote in an email to the News. “The implications are many. This data adds to a growing body of literature demonstrating the profoundly high risk of COVID-19 in nursing home residents.”

The study made use of Connecticut’s testing program for SARS-CoV-2 and collaborated with multiple state laboratories that had been compiling reports of positive cases since the beginning of the pandemic, Parikh described.

He wrote that researchers analyzed these results to identify nursing homes that were currently experiencing or at risk of experiencing outbreaks in their facilities. With increased testing around the state by the spring of 2020, researchers were able to test all nursing home residents on a weekly basis, with the goal of identifying and preventing outbreaks while also gathering useful data on COVID-19 among this vulnerable elderly population.

“As the summer progressed, it became clear that many elderly in nursing homes were having multiple positive tests, often separated by weeks or months from one another,” Parikh described. “The question then became, ‘Are these actually reinfections, or are they just lingering cases, or false positives?’”

He wrote that in the summer of 2020, the Centers for Disease Control and Prevention updated their recommendations, stating that any repeat positive tests within 90 days of an initial positive did not require a follow-up, as they “more likely represent[ed] persistent shedding of viral RNA than reinfection.”

Raj and Indra Nooyi Professor of public health Albert Ko explained possible scenarios that would cause repeated positive tests when an individual has not actually been infected a second time.

“Why would somebody have a positive test after the first test? We know that people can remain PCR positive [for COVID-19] for longer than … other viral diseases,” Ko said. “The median is about 18 days.”

Ko said that there are three probable reasons that the researchers were observing repeat positive tests in nursing homes. The first option was the case of “persistent positives” — residents that were only infected once but were still showing up as positive even 90 days after the initial infection — because of weakened immune systems due to age.

The second option, Ko described, was that more “persistent positives” were recorded in nursing home residents than the general population because these individuals were getting tested more often. The third and final option is that these nursing home residents were indeed reinfected within the 90-day window.

“It’s really hard to tease those three things out, and we still don’t know,” Ko said.

Parikh also described some of the limitations of the study — namely, that researchers could not obtain patient samples for a process called comparative sequencing. This meant it was not possible to demonstrate if the viral genome that caused the initial reported infection in a nursing home resident was equivalent to the virus that caused a repeat positive test, Parikh said.

“This just reflects the challenge and reality of doing research in the setting of a public health emergency,” Parikh wrote. “In these cases, one needs to explore other data that may further support whether these tests represent true reinfections.”

He noted that they did find some evidence to support the possibility of reinfection. For instance, 80 percent of participants who died during the study had one or more negative intervening tests.

But Parikh explained that while the researchers faced obstacles to collecting complete data, they do know that elderly individuals tend to be more medically frail and that living in highly congregated settings like nursing homes put them at greater risk of exposure to COVID-19.

When one considers this information with the facts of biological “aging” of the immune system and the possibility that reinfections can occur as soon as three months after an initial infection, Parikh explained, it highlights the need to continue with COVID-19 testing in nursing homes.

“We can’t assume that because COVID-19 has come through a facility, or that a resident has already had COVID-19, that they are no longer at risk,” Parikh wrote. “Indeed, we are also seeing that the duration of protection after vaccination (in addition to after natural infection), is less in the elderly, than in younger populations.”

On Aug. 8, Gov. Ned Lamont issued an executive order that all long-term care facility staff in Connecticut must be vaccinated against COVID-19 and receive their first dose of the vaccine no later than Sept. 7. Any long-term care facilities that do not comply with this rule are subject to a $20,000 fine per day.