A recent study showed that SARS-CoV-2, the virus that causes COVID-19, can infect a person for more than 200 days in an atypical case. The study was published in the journal Frontiers in Medicine.
The atypical case of SARS-CoV-2 infection was part of a study involving 38 Brazilian patients, followed weekly between April and November 2020 by researchers affiliated with the Pasteur-USP scientific platform, a partnership between the French Pasteur Institute, the University of São Paulo ( USP) and the Oswaldo Cruz Foundation (Fiocruz) in Brazil. Patients were followed up until they tested negative two or three times in a row with RT-qPCR.
The study was supported by FAPESP. It served as a warning about the risk of restricting quarantine for COVID-19 patients to seven, ten, or even 14 days after a positive test result, as originally mandated by disease control protocols. It has also reinforced the importance of vaccinations, social distancing and masks. “Of the 38 cases we tracked, two men and a woman were atypical in the sense that the virus was continuously detected in their bodies for more than 70 days. Based on this result, it can be said that about 8 percent of people infected with SARS-CoV-2 can transmit the virus for more than two months without necessarily showing any symptoms at the last stage of the infection,” said Marielton dos Passos Cunha, first author of the paper.
The study was conducted while he was an intern at the Pasteur-USP scientific platform. “We wanted to know if the 14-day period was really long enough for the virus to stop being detected. study patients remained positive for 71 to 232 days,” said Paola Minoprio, one of the Platform coordinators and principal investigator of the study.
This is not the first evidence that the virus may remain active longer than expected, even in patients with mild symptoms. In early 2021, researchers at the Institute of Tropical Medicine of the University of São Paulo (IMT-USP) in Brazil analyzed 29 nasopharyngeal secretions from patients who tested positive for COVID-19. The material was collected at a government primary health care center ten days after symptom onset and inoculated into laboratory-grown cells. In 25% of cases, the viruses present in the samples were able to infect cells and reproduce them in vitro. Thus, theoretically, other people could become infected if they came into contact with saliva droplets produced by 25 percent of these patients during the collection of material.
The risk was even higher for people with weakened immune systems. In a paper published in June 2021, researchers at the same university’s School of Medicine (FM-USP) described a case of infection that lasted at least 218 days. The patient was about 40 years old and had undergone aggressive cancer treatment before contracting COVID-19.
An article published in the New England Journal of Medicine in early December 2020 reported the case of a 45-year-old immunocompromised man with an autoimmune blood disorder in whom the virus continued to replicate for 143 days. And an article published in Cell in late December tells of a leukemia patient who kept replicating the virus for at least 70 days, even though she did not show symptoms of COVID-19. However, this week the Brazilian Ministry of Health reduced the recommended self-isolation period from ten to seven days for patients with mild or moderate symptoms, and to five days for people without symptoms if they test negative.
At the end of 2021, the US Centers for Disease Control and Prevention (CDC) reduced their recommendations from 10 days to 5 days for asymptomatic patients, provided they continue to wear a mask and test negative for COVID-19. In a study led by Minoprio, the difference between women and men in the duration of viral activity was insignificant (on average 22 days and 33 days, respectively). Of the three atypical cases, the virus remained detectable for 71 days in a woman and 81 days in one in two men. None of them had comorbidities and all had mild symptoms of COVID-19.
The other atypical man continued to test positive for coronavirus for 232 days (April-November 2020), after which he tested negative three times by RT-qPCR. He has had HIV, the virus that causes AIDS, since 2018, but thanks to antiretroviral therapy, he had no detectable viral load. “The fact that he is HIV seropositive does not mean that he is more susceptible to other infections as he has been on therapy since he was diagnosed. His ability to respond to an infection caused by another agent is comparable to that of any other person, and indeed, he reacted to the coronavirus when infected. He doesn’t have suppressed immunity like cancer patients, people with autoimmune diseases or people who have had transplants, for example,” Minoprio said.
According to researchers, his HIV-positive status does not explain the long duration of his coronavirus infection. Many patients co-infected with HIV and SARS-CoV-2 will need to be compared with an appropriate control group to see if any host genetic or immune traits could be associated with such prolonged shedding of the virus. The patient underwent weekly tests that detected the persistence of the infection, and virus samples were regularly sequenced to show that this was not a case of reinfection and that the virus not only continued to multiply, but also mutated.
The strategies used by the virus to evade the immune system during infection have been mapped, showing that the viral load dropped when there were more neutralizing antibodies and that the virus was able to bypass the body’s defenses to increase the load again. The cycle was repeated, causing more antibodies to be produced until the viral load dropped again. “It is important to monitor these patients because we can learn more about how the virus mutates and what mutations can cause dangerous variants,” Cunha said.
The patient in the study was infected with the B.1.1.28 virus lineage, which entered Brazil in early 2020. The researchers found no mutations in the virus isolated from the patient that would justify classifying it as more transmissible or more resistant to the virus. the immune system. The Pasteur-USP scientific platform continues to investigate these and other cases. The 38 patients analyzed in the Minoprio-led study are part of a bank of blood and nasopharyngeal samples collected from 721 people who showed symptoms associated with this coronavirus.
“From these samples, fresh data will be obtained, and we may be able to provide more tangible explanations for these atypical cases,” Cunha said. “These cases are further evidence that wearing masks and social distancing are the best ways to fight the pandemic. If a person is not retested 14 days after testing positive, they may still be shedding active viruses and have the potential to infect others,” facilitating community transmission of the virus,” Minoprio said.
“It is very important to track infected people so that we can learn more about the mutations, new variants and transmissibility of SARS-CoV-2,” Minoprio concluded. (API)
(This story has not been edited by the Devdiscourse staff and is automatically generated from a syndicated feed.)