A general view of the Centers for Disease Control and Prevention (CDC) headquarters in Atlanta.
Tami Chappell | Reuters
A new CDC study found that some elderly people who apparently recovered from the coronavirus later had a second, even worse infection, suggesting that asymptomatic or mild cases may not offer much protection against re-infection with Covid-19 not.
The study, which was published Thursday in the Centers for Disease Control and Prevention’s weekly report on morbidity and mortality, looked at two separate outbreaks that occurred three months apart in a competent nursing home in Kentucky. Between mid-July and mid-August, 20 residents and five health care professionals tested positive for the virus, according to the study.
The second outbreak between late October and early December was worse – 85 residents and 43 health workers were positive about the virus. Among the residents who tested positive during the first outbreak and still lived in the facility, five of them tested positive a second time, more than 90 days apart from their first positive test.
Although Covid-19 re-infections occur, they are usually rare.
Through the regular surveillance after the first outbreak, all five residents had at least four negative tests between the outbreaks, indicating that they may later be re-infected with the virus, the study found. Re-infection means that a person who had Covid-19 recovered and got it again, according to the CDC.
“The exposure history, including the timing of roommate infections and the new onset of symptoms during the second outbreak, suggests that the second positive RT-PCR results represent new infections after the patients apparently cleared the first infection,” said Alyson Cavanaugh, one writing. of the researchers who led the study.
While only two of the five residents experienced mild symptoms during the first outbreak, all five residents who may have been re-infected showed signs of illness a second time. The two residents who reported symptoms during the first outbreak, according to the study, experienced worse symptoms during the second infectious episode. One resident was admitted to the hospital and subsequently died.
According to the researchers of the study, it was ‘remarkable’ because it indicates the possibility that people who show mild to no symptoms during their first infections ‘do not provide a sufficiently robust immune response to prevent reinfection.’ The results “indicate the possibility that diseases may be worse during a second infection.”
“The findings of this study highlight the importance of maintaining public mitigation and protection strategies that reduce the risk of transmission, even among individuals with a history of COVID-19 infection,” Cavanaugh wrote.
The study noted some limitations. Because samples were not stored, researchers were unable to perform genomic sequencing, a laboratory technique that breaks down the genetic code of the virus, to confirm reinfection. They also said: “There are no additional test results to support the initial test result as a true positive”.
It is suspected that the risk of re-infection for the general population is still low, but residents of nursing homes may be particularly at risk given their combined existence and a large number of exposures, according to the study.
‘Skilled nursing homes should use strategies to reduce the risk of SARS-CoV-2 transmission among all residents, including those who have previously had a COVID-19 diagnosis,’ Cavanaugh wrote.