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A study confirming the first case of reinfection by the new coronavirus in the United States, the fifth worldwide, indicates that exposure to the virus may not confer full immunity.
The work, published this Monday in the scientific journal Lancet, analyzes the case of a 25-year-old young man who tested positive for two different SARS-CoV-2 infections in 48 days, confirming that a second infection can occur in a short time . time and may be more serious, as was the case.
The results of this study, funded by the National Institute of General Medical Sciences and conducted by researchers from the Nevada State Laboratory of Public Health and the University of Nevada Reno School of Medicine, indicate that exposure to COVID-19 can not translate into guaranteed full immunity and that further investigations are required on reinfection cases.
In this first study to confirm a case of Covid-19 reinfection in the US, researchers found evidence that an individual with no known immune disorders or underlying conditions was infected with SARS-CoV-2 in two different situations.
The 25-year-old patient living in Washoe County, Nevada, was infected with two different variants of SARS-CoV-2 over a 48-day period.
The second infection was more severe, leading to hospitalization with oxygen support, which may indicate that previous exposure to COVID-19 may not translate into guaranteed full immunity.
The study authors note that all people, previously diagnosed or not, should take the same precautions to prevent SARS-CoV-2 infection.
After testing positive for SARS-CoV-2 in April 2020, the patient tested negative for the virus on two different occasions.
In June 2020, after experiencing severe Covid-19 symptoms, including fever, headache, dizziness, cough, nausea, and diarrhea, the patient was hospitalized and had a second positive test. He has been discharged from the hospital and is now recovered.
“There are still many unknowns about SARS-CoV-2 infections and the immune system response, but our findings indicate that a previous SARS-CoV-2 infection may not protect against future infections,” said the study’s lead author. , Mark Pandori, PhD, of the Nevada State Public Health Laboratory, located at the University of Nevada (Reno School of Medicine).
“It is important to note that this is a unique finding. Although more research is needed, the possibility of reinfections may have significant implications for our understanding of immunity to COVID-19, especially in the absence of an effective vaccine,” he said, arguing that the People who test positive for SARS-CoV-2 should continue to take serious precautions, including social distancing, wearing face masks, and hand washing.
At least four other reinfection cases have been confirmed in Belgium, the Netherlands, Hong Kong and Ecuador.
However, only the reinfection case in Ecuador showed worse disease results than the first infection.
“We need more research to understand how long immunity can last for people exposed to SARS-CoV-2 and why some of these secondary infections, although rare, are more serious,” Pandori said.
“So far, we have seen only a few cases of reinfection, but that does not mean that there are not more, especially since many cases of covid-19 are asymptomatic. At the moment, we can only speculate on the cause of the reinfection,” he said .
As in the case of reinfection in Ecuador, the North American patient experienced an increase in the severity of symptoms in his second infection, while the cases of Belgium, Holland and Hong Kong did not show differences in the severity of symptoms.
The authors put forward several hypotheses to explain the severity of the second infection, including the possibility that the patient encountered a very high load of the virus that caused a more acute reaction the second time.
Another of the advanced hypotheses is that the patient has had contact with a more virulent version of the virus or that the mechanism of increase is dependent on antibodies (which means that the presence of antibodies can worsen a subsequent infection) as has already happened with other diseases such as dengue.
Finally, another alternative explanation would be a simultaneous coinfection of both strains of the virus. However, that would mean that the second strain would not have been detected in April 2020.
The authors acknowledge that the study is limited because it was not possible to perform any evaluation of the immune response to the first episode of SARS-CoV-2 infection or the effectiveness of immune responses during the second episode.
The researchers also note that this case and other confirmed cases of reinfection occurred among patients who had symptoms of COVID-19, meaning that there is a possibility that many infections and / or reinfections between individuals may be asymptomatic and therefore, they are likely to remain. not detected in current tests.
“Overall, there is a lack of complete genomic sequencing of COVID-19 positive cases both in the US and around the world, as well as a lack of detection and testing, limiting the ability to diagnose, monitor, and get genetic testing of the virus, “he said.
The covid-19 pandemic has already claimed more than one million seventy-seven thousand deaths and more than 37.5 million cases of contagion worldwide, according to a report prepared by the French agency AFP.
Today, Portugal counts 14 more deaths related to covid-19 and 1,249 new cases of infection by the new coronavirus.
The disease is transmitted by a new coronavirus detected in late December in Wuhan, a city in central China.
After Europe succeeded China as the center of the pandemic in February, the American continent is now the one with the most confirmed cases and the most deaths.
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