Nevada man could be first case of coronavirus reinfection in US, his illness was more severe second time: Study
The researchers conclude that it is possible for people to become infected multiple times by Covid-19, but the generalizability of this finding is not known
A 25-year-old man from Nevada could be the first confirmed case of Covid-19 reinfection in the US, and the fourth such documented case globally so far. Forty-eight days after testing positive for Covid-19 in April and after testing negative consecutively twice, the patient in Nevada’s Washoe County tested positive again in June. Recently, researchers have reported cases of reinfection in a patient in Hong Kong and two patients in Europe (one in Belgium and another in the Netherlands).
Led by the Nevada State Public Health Laboratory (NSPHL), University of Nevada, scientists from the university’s Reno School of Medicine, and Washoe County Sheriff's Office, among others, have studied this case. According to the authors, genetic sequencing of the virus indicates the patient was infected with two different versions of the virus. “The data herein support an instance of reinfection with SARS-CoV-2 (the virus that causes Covid-19). The genomes of the patient’s virus samples were sequenced in April and June, displaying significant genetic discordance between the two cases, implying the patient was infected twice,” writes the team in their analysis, which has been published as a pre-print. They add, “We conclude that it is possible for humans to become infected multiple times by SARS-CoV-2, but the generalizability of this finding is not known.”
The patient’s illness was more severe the second time and he had to be hospitalized, where he received oxygen support. Yale School of Medicine professor Dr Akiko Iwasaki wrote in a tweet that unlike the patient in Hong Kong, where the first case of coronavirus reinfection was documented, “the immune system did not protect this person (Nevada patient) from reinfection or disease.”
A 25 yr old patient in Nevada has a confirmed case of #COVID19 reinfection (48 days apart between 1st and 2nd PCR).— Prof. Akiko Iwasaki (@VirusesImmunity) August 28, 2020
This time, unlike the case in Hong Kong, the immune system did not protect this person from reinfection or disease. (1/n)https://t.co/9gMThBoMu2
An implication of the US report is that initial exposure to the Covid-19 may not result in a level of immunity that is 100% protective for all individuals, according to the research team. With regard to vaccination, this is an established understanding, with influenza regularly demonstrating the challenges of effective vaccine design, they add. The authors said it is crucial to note that the frequency of such a phenomenon “is not defined by a singular case study.” They say that this may represent a rare event, but emphasize that the lack of comprehensive genomic sequencing of positive cases in the US and worldwide limits the public health surveillance required to find these cases.
“We examined the genomic material of the viruses and samples to investigate this. It is just one finding, but it shows that a person can possibly become infected with SARS-CoV-2 a second time,” says Dr Mark Pandori, director of NSPHL.
The US case study
The resident of Reno tested positive for Covid-19 in April at a community-based testing event held by the Washoe County Health District on April 18. The patient indicated symptoms consistent with a viral infection, such as sore throat, cough, headache, nausea, and diarrhea. During isolation, he indicated a resolution of his symptoms on April 27.
The patient was subsequently tested and was found negative for Covid-19 for specimens collected on May 9, and May 26. The patient continued to feel well until May 28. On May 31, he sought care with self-reported fever, headache, dizziness, cough, nausea, and diarrhea. A chest X-ray was performed and he was discharged home. “Five days later, on June 5, the patient presented to a family care doctor and was found to be hypoxic (a condition that happens when the body does not get enough oxygen), and was instructed to go to the emergency department. The patient was hospitalized that day and tested for Covid-19. The patient required ongoing oxygen support and reported symptoms that included myalgia (muscle pain), cough, and shortness of breath. The patient tested positive for Covid-19,” the findings reveal.
The investigators conducted “identity testing” on the specimens and lab samples evaluated in the study to verify the specimens were from the same person. Embedded in the genomic material of SARS-CoV-2 is a detailed code that experts say may provide insight into a better understanding of this virus. “A virus has a biological genome like all living things. Since March, the NSPHL has analyzed the genomic RNA of approximately 200 positive Covid-19 samples from Nevadans who have tested positive for Covid-19. The power of genomic information could turn the tables in the fight against the coronavirus,” explains Pandori.
Based on their findings, the researchers caution that reinfection cases are a potential warning sign that it is possible to catch Covid-19 more than once and with unpredictable severity. “If reinfection is possible on such a short timeline, there may be implications for the efficacy of vaccines developed to fight the disease. It may also have implications for herd immunity. It is important to note that this is a singular finding. It does not provide any information to us with regard to the generalizability of this phenomenon,” writes Pandori.
According to experts, there are currently many more unknowns than knowns about immune responses to Covid-19. “After one recovers from Covid-19, we still do not know how much immunity is built up, how long it may last, or how well antibodies play a role in protection against reinfection. This is a novel disease. We still have a steep learning curve ahead and lots of work to do, especially as inconvenient truths arise,” says Pandori.