A study by researchers at the Public Health Laboratory of the State of Nevada and the University of Nevada, in the United States, confirmed the first case of reinfection by Covid-19 in the country. This is the fifth case recognized worldwide, which indicates that exposure to the virus may not bring total immunity, contrary to popular belief.
According to the survey, published on Monday (12) in the The Lancet Infectious Diseases, the analyzed patient tested positive for two infections by different variants of Sars-CoV-2 within 48 days, confirming that a second can occur in short periods. The 25-year-old man did not belong to any risk group or had previous health problems. In addition, in the period between infections, he tested negative for the coronavirus twice.
According to the research, the second infection of the patient was more serious than the first, and he needed to be hospitalized and have oxygen support. For this reason, the authors state that all individuals – previously diagnosed or not – should continue to take the recommended precautions, such as avoiding crowding, washing their hands frequently and wearing a mask in public places.
“There are still many unknowns about Covid-19 infections and the response of the immune system, but our findings indicate that a previous infection may not necessarily protect against future ones,” said lead author Mark Pandori in a note. According to him, the analysis raises new questions for understanding coronavirus immunity, especially while there is no effective vaccine.
At least four other cases of reinfection have already been confirmed in Belgium, the Netherlands, Hong Kong and Ecuador. However, only the Ecuadorian patient had a worse picture of the disease in the second infection, like the American.
“We need more research to understand how long immunity can last for people exposed to Sars-CoV-2 and why some of these second infections, although rare, are more serious,” said Pandori.
About the survey
The authors acknowledge that the evaluation of an immune response (for example, neutralizing antibodies) was not carried out, neither in the first nor in the second case of infection of the analyzed patient.
However, there is the possibility that the man contracted a stronger virus in the second infection, or that Covid-19 was in his body and there was a way of deactivating his identification. In addition, scholars also explain that there is a possibility that many infections may be asymptomatic and therefore are likely to remain undetected in current tests.
Commenting on the research, Akiko Iwasaki, a professor at Yale University, USA, who was not involved in the study, says: “as more cases of reinfection arise, the scientific community will have the opportunity to better understand the correlates of protection and with how often natural infections with Sars-CoV-2 induce this level of immunity. This information is the key to understanding which vaccines are capable of crossing that threshold to confer individual and collective immunity. ”