Reinfections could be more likely among those with a mild first case of COVID-19: case study
Specimens to be tested for COVID-19 are seen at LifeLabs after being logged upon receipt at the company's lab, in Surrey, B.C., on Thursday, March 26, 2020. THE CANADIAN PRESS/Darryl Dyck
TORONTO -- Five seniors in a nursing facility in Kentucky were reinfected with COVID-19 after recovering from a mild case of the coronavirus, suggesting that some people may be more at risk for reinfection, and even experiencing worse outcomes the second time.
The situation was described in a new case study published by the U.S. Centers For Disease Control and Prevention (CDC) on Thursday, which tracked two outbreaks in a Kentucky skilled nursing facility, which is a home for those requiring short-term, rehabilitative care.
The facility experienced its first outbreak in July, when a member of the health-care team tested positive for COVID-19. Those affected by the outbreak were moved to a separate COVID-19 unit within the facility. Twenty residents and five members of the medical staff contracted the virus. Eight residents had to be hospitalized and five residents died.
Everyone was tested weekly, even after the outbreak was deemed to be over.
“A total of 597 facility-ordered RT-PCR tests were performed in September, and 331 tests were performed during October 1–29; all results were negative,” the case study stated.
But then, on Oct. 30, a second outbreak began.
Two residents tested positive, and between the end of October and Dec. 7, 85 residents and 43 medical staff members contracted the virus. Fifteen residents died in the second outbreak.
Twelve residents who tested positive in the first outbreak were still living at the facility in October, and five of them tested positive in the second outbreak as well.
Health officials deemed these five to officially have recurrent cases of COVID-19.
Four of them were women, and all were between the ages of 67 and 99 years. All of them also had more than three chronic health conditions, and had tested negative for COVID-19 at least four times consecutively in between their two infections.
And for all five, their second infection was much worse.
“Although three of the five patients with recurrent COVID-19 were asymptomatic during their first infectious episode, all five experienced symptoms during their second infectious episode; the two patients who were symptomatic during the first outbreak experienced more severe symptoms during the second infectious episode compared with the symptoms they had during the first outbreak,” the case study stated.
For one of the five, the reinfection was fatal. That person was among the fifteen residents who died during the second outbreak.
COVID-19 reinfection is relatively rare, and there isn’t much data on how exactly it works — but much of the research so far has suggested that those who have a mild first case are more likely to become reinfected, and that the second case is unlikely to be severe.
This new case study out of Kentucky shows that a second infection can be serious, driving the need for more research into this phenomenon.
“The finding that all five patients with recurrent COVID-19 had either asymptomatic or mildly symptomatic courses during their first infections is noteworthy, suggesting the possibility that asymptomatic or mildly symptomatic initial infections do not produce a sufficiently robust immune response to prevent reinfection,” the case study stated in its conclusions.
The CDC acknowledged there were limitations to the data, such as the fact that specimens were not stored for genomic sequencing to confirm beyond a shadow of doubt that these were reinfections.
The residents all had contributing factors, such as age and underlying conditions, which made them more at risk to the virus.
That vulnerable populations could be more at risk of reinfection is significant. It reminds us that we can’t assume the worst is over if a person in a vulnerable population recovers once from COVID-19, the study said.
“These findings highlight the importance of maintaining public health practices that reduce transmission risk, even among persons who have previously received a positive SARS-CoV-2 test result.”
Canada has had three confirmed cases of reinfection, all in B.C., although several other provinces have reported having cases under study to see if they are true reinfections.