A case study by researchers from UMass Medical School and The Broad Institute of MIT and Harvard, published in Annals of Internal Medicine April 20, has documented evidence of COVID-19 reinfection in a patient who previously had the disease, confirming the second episode was not a relapse.
Researchers used viral genomic sequencing to distinguish whether the later positive samples in a 61-year-old patient with a history of liver transplant bore the same genetic code as the SARS-CoV-2 sample from his first infection, slightly more than three months earlier. COVID-19 tests performed in between the two positive samples showed the patient had cleared the virus.
The study highlights the importance of widespread vaccination against COVID-19 to protect against spread of the virus in the community, and for people with compromised immune systems, even if vaccinated, to remain vigilant in terms of masking and distancing, according to the authors.
“If there is one thing that COVID has taught us,” said author Nicole Marie Theodoropoulos, MD, associate professor of medicine at UMass Medical School, “it is how to think on the fly as new information comes in every day.”
“We didn’t have much information about relapsing infection, so there were a lot of possibilities,” said Dr. Theodoropoulos, director of transplant infectious diseases at UMass Memorial Medical Center. “I think it was really important that everyone went through this extremely extensive analysis to prove that this was a reinfection.”
Patients who have had organ transplants have suppressed immune systems to prevent their body from rejecting the transplanted organ. According to the study authors, the patient may have been susceptible to reinfection due to the possible lack of antibody response after the first infection.
“Having COVID-19 decreases the risk of getting it again in the general population by around 84 percent,” Theodoropoulos said. “But immunocompromised people are more likely to get reinfected.”
Stuart M. Levitz, MD, professor of medicine and one of the authors, said this case study was possible because UMass Memorial Medical Center has kept a biorepository of all the positive specimens from its patients’ nasopharyngeal swabs, used for PCR testing. The samples were shipped on dry ice to the Broad Institute in Cambridge for whole genome sequencing.
“So, they were able to identify every single RNA base of the virus and then compare the patient’s second sample with the original virus,” Dr. Levitz said. “That was really the big question: Is this virus a new infection? Or was the patient never able to control his own infection?”
Levitz said the patient’s new infection was a different strain of SARS-CoV-2 from the first, but neither was what is known as a variant of concern, such as the more infectious or potentially harmful strains originally identified in the United Kingdom, South Africa or Brazil.
The implications of this finding for the public, as well as for people with compromised immune systems because of a transplant, cancer treatment, HIV/AIDS or some medications for autoimmune disorders, are that even if someone has had COVID-19, it is possible to get it again, Theodoropoulos said.
Patients who have had a transplant are still encouraged to get vaccinated, she said, which they can safely do as early as one month after their transplant surgery.
But, the authors said, it is crucial for people who have close contact with an immunocompromised host to be vaccinated.
“By getting the vaccine, you’re not only protecting yourself, but you’re protecting all these other people who can’t have a good response and make antibodies to the vaccine,” said Levitz. “Anybody who is immunosuppressed is relying on the rest of us. What might be a minor COVID infection in you could be a deadly one for our patients.”
Jennifer S. Daly, MD, professor of medicine and a study author, said UMass Memorial Medical Center is a major liver transplant center, on track to perform an estimated 100 transplants this year. The clinical system also performs kidney transplants and some pancreas transplants and has seen COVID-19 in liver and kidney transplant patients.
“Fortunately, the renal patients are getting immunized for COVID in dialysis centers, which was helping us; and now it’s available to everybody, so hopefully we get more patients vaccinated before their transplant, when their immune system has a greater chance of a robust immune response,” Dr. Daly said.
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