Washington: A new study found that SARS-CoV-2, the virus that causes COVID-19, can infect humans for more than 200 days in atypical cases.
This study was published in “Forefront of Medical Journals”.
Atypical cases of SARS-CoV-2 infection were followed weekly from April to November 2020 by researchers at the Pasteur-USP Science Platform, a partnership between the Pasteur Institute and the University in France38. It was part of a study of human Brazilian patients. Patients from Brazil’s Sao Paulo (USP) and Oswaldo Cruz Foundation (Fiocrus) were followed up to two or three consecutive negative tests by RT-qPCR.
This study was supported by FAPESP. This serves as a warning about the risk of limiting the quarantine of COVID-19 patients to 7, 10, and even 14 days after being positive, as originally prescribed in the Protocol for Fighting Disease. I did. It also strengthened the importance of vaccination, social distance, and wearing a mask.
“Of the 38 cases we followed, two men and one woman were atypical in the sense that the virus was continuously detected for more than 70 days. Based on this result, infected individuals. About 8% of SARS-CoV-2 can infect the virus for more than 2 months without necessarily showing symptoms in the final stages of infection, “said Marielton dos Passos Cunha, the first author of this article. Says.
This study was conducted when he was a postdoctoral fellow on the Pasteur-USP Scientific Platform.
“I wanted to know if 14 days was really long enough to stop detecting the virus. I concluded that it wasn’t. It can take a month for a patient to become negative. In some cases, patients remained positive for 71-232 days in the study, “said Paola Minoprio, one of the platform’s coordinators and principal investigator of the study.
This is not the first evidence that the virus can remain active longer than expected even in patients with mild symptoms. In early 2021, researchers at the Institute of Tropical Medicine (IMT-USP) at the University of Sao Paulo in Brazil analyzed 29 samples of nasopharyngeal secretions from COVID-19-positive patients.
On the 10th day after the onset of symptoms, the cells were collected at a public primary health center and inoculated into the cells grown in the laboratory. In 25% of cases, the virus present in the sample infected the cells and was able to replicate them in vitro. Therefore, in theory, if other people come into contact with saliva droplets excreted by 25% of these patients when the material is collected, they can become infected.
People with weakened immunity seem to be at even greater risk. In a paper published in June 2021, researchers at the same university’s School of Medicine (FM-USP) described a case of an infectious disease that lasted at least 218 days.
The patient was about 40 years old and had been actively treated for cancer before becoming infected with COVID-19.
An article published in the New England Journal of Medicine in early December 2020 reported a case of a 45-year-old man with immunodeficiency in an autoimmune blood disorder in which the virus continued to replicate for 143 days. An article published in Cell in late December also outlined a case study of a female leukemia patient who had no symptoms of COVID-19 but had the virus replicated for at least 70 days.
Still, this week, the Brazilian Ministry of Health has reduced the recommended period of self-quarantine to 10 to 7 days for patients with mild or moderate symptoms and 5 days for asymptomatic patients if the test is negative. did.
At the end of 2021, the US Centers for Disease Control and Prevention (CDC) reduced recommendations from 10 days to 5 days, provided that asymptomatic patients continue to wear masks and test negative for COVID-19. Did.
In a study led by Minoprio, the difference between females and males in terms of duration of viral activity was not significant (mean 22 and 33 days, respectively). For three atypical cases, the virus remained detectable in females for 71 days and in one of two men for 81 days. None of them had comorbidities and all had mild symptoms of COVID-19.
Another atypical man continued to test positive for coronavirus for 232 days (April-November 2020), followed by three negative tests by RT-qPCR. He has been infected with HIV, the AIDS-causing virus since 2018, but thanks to antiretroviral therapy, the viral load could not be detected.
“The fact that he is sera-positive for HIV does not mean that he is susceptible to other infections because he has been treated since he was diagnosed. He responds to infections with other drugs. The ability of is comparable to that of other individuals. Certainly he responded to coronavirus when infected. For example, cancer patients, people with autoimmune disease, transplanters who are not immunosuppressed. “Minoprio said.
According to researchers, his HIV-positive status does not explain the long-term infection with his coronavirus. Many patients co-infected with HIV and SARS-CoV-2 are compared with appropriate controls to determine if the host’s genetic or immune characteristics are associated with such long-term viral shedding. is needed.
Patients underwent weekly tests to detect persistence of infection, and virus samples were regularly sequenced, indicating that the virus was mutating as well as continuing to replicate, not in the case of reinfection. ..
The strategy used by the virus to escape the immune system during infection was mapped to the fact that increasing neutralizing antibodies reduced the viral load and allowed the virus to evade the body’s defenses and increase the load again. Shown. This cycle was repeated, forcing more antibody production until the viral load decreased again.
“It’s important to observe such patients because we can learn more about how the virus mutates and which mutations can cause the mutations of concern,” Cunha said.
Patients in the study were infected with strain B.1.1.28, which invaded Brazil in early 2020. Researchers did not detect mutations that could justify classifying the virus isolated from the patient as more contagious or more resistant. 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 secretion samples collected from 721 patients who exhibited symptoms associated with this coronavirus.
“Fresh data can be obtained from these samples and can generate a clearer explanation for these atypical cases,” Cunha said.
“These cases are further evidence that wearing a mask and social distance are the best ways to control a pandemic. Active virus, even if the person is not tested again 14 days after a positive test. It can be discharged and infect others. It contributes to the communication of the community. “
“It is very important to track infected people so that we can learn more about mutations, novel variants and the infectivity of SARS-CoV-2,” Minoprio concludes.
Studies show that SARS-CoV-2 may remain active for longer than the recommended quarantine period, Health News, ET HealthWorld.