Study: Sars-CoV-2 can stay in the body longer than quarantine – 01/14/2022

A 38-year-old man, who had mild symptoms of COVID-19 for 20 days, remained for 232 days with the new coronavirus being detected in the body and mutating. Had he not received constant medical monitoring, maintained social distancing and worn a mask, he could have spread the pathogen for more than seven months.

The atypical case of SARS-CoV-2 infection is part of a group of 38 patients followed up weekly, at the beginning of the pandemic, by researchers from the Pasteur-USP Scientific Platform (PCPU). Patients were followed until two or three consecutive RT-qPCR tests were negative.

The study, supported by Fapesp and published in the journal Frontiers in Medicine, is a warning about the risk of releasing patients with COVID-19 after seven, ten or even 14 days of testing positive, as provided for in the initial protocols to combat COVID-19. In addition, it reinforces the need for vaccination and to maintain social distance and the use of masks.

“Of the 38 cases that we followed, two men and one woman were atypical, remaining more than 70 days with the detectable virus in the body. Based on this result, we can say that about 8% of those infected with SARS-COV-2 may have the ability to transmission of the virus for more than two months, without necessarily showing any symptoms during the final phase of the infection”, explains Marielton dos Passos Cunha, first author of the study, carried out during a postdoctoral internship at PCPU.

“We wanted to know if 14 days were really enough for the virus to stop being detectable. We found that it was not. On average, it can take a month for the test to be negative and, in some cases in this study, positivity extended from 71 to 232 days”, says Paola Minoprio, one of the coordinators of PCPU and leader of the study.

This is not the first evidence that even in patients with mild symptoms the virus can remain active in the body for longer than expected. In early 2021, researchers from the IMT-USP (Institute of Tropical Medicine, University of São Paulo) analyzed 29 samples of nasopharyngeal secretions from people who tested positive for covid-19.

The material was collected at a Basic Health Unit on the tenth day after the onset of symptoms and, in the laboratory, inoculated into cell cultures. In 25% of cases, the virus present in the samples was able to infect cells and replicate in vitro.

In theory, therefore, people who had contact with droplets of saliva expelled by 25% of these patients during the period in which the material was collected could still be contaminated.

The risk seems to be even greater in the case of individuals with some type of compromised immune system. Researchers at the USP School of Medicine described, in June last year, a case of infection that lasted at least 218 days. The patient, approximately 40 years old, had undergone aggressive cancer treatment before contracting Covid-19.

In November 2020, it was described in the New England Journal of Medicine the case of an autoimmune hematological disease carrier – also male and in his 40s – who harbored the replicating virus in his body for 143 days. And in an article published in Cell, the case of a woman with leukemia was reported in whose body SARS-CoV-2 continued to replicate for at least 70 days, although she no longer manifested symptoms of covid-19.

Still, the Ministry of Health this week reduced the isolation time from ten to seven days for people with mild to moderate symptoms. The quarantine period can be reduced to five days if the patient is symptom-free and retests with a negative result.

At the end of 2021, the US Centers for Disease Control (CDC) reduced the recommended time of isolation for asymptomatic patients from ten to five days, as long as they continue to wear a mask and test negative for the disease.

Mutations in the host

In the study led by Minoprio, the difference in time of viral activity between women and men was not significant, with an average of 22 days for the first group and 33 for the second. Of the three atypical cases, a woman remained with the detectable virus for 71 days, and a man, 81 days. These patients had no comorbidity and had mild cases of covid-19.

The third atypical patient, male, remained positive for the virus for 232 days, from April to November 2020, until three RT-qPCR tests were negative. The man has been living with HIV, the virus that causes AIDS, since 2018, but his viral load remains undetectable with treatment.

“HIV positivity does not mean that he is more susceptible to other infections, as he has been on treatment since diagnosis. His ability to respond to an infection with another agent is comparable to that of anyone, so much so that he responded to the coronavirus from the beginning of the infection. This is not an immunosuppressed individual [como pessoas em tratamentos de câncer, doenças autoimunes ou transplantados, por exemplo]”, informs Minoprio.

According to the researchers, the fact of living with HIV still does not explain the prolonged time of infection. It would be necessary to evaluate many other patients who have both HIV and SARS-CoV-2 and compare them with an appropriate control group to understand, for example, if there is any genetic or immunological characteristic of the host that would be linked to the late elimination of the virus.

In addition to the weekly tests that detected the persistence of the infection, the patient had samples of the virus sequenced regularly. The analyzes made it possible to verify that it was not a case of reinfection. Furthermore, they showed that the virus continued not only to replicate but also to mutate.

During the infection, it was possible to map the strategies of the virus to get rid of the immune system. When there were more neutralizing antibodies, the viral load went down. The virus then managed to evade the defenses and increase its concentration and the cycle was then repeated, forcing the production of new antibodies and the decrease of circulating viruses.

“It’s important to observe patients like this because we can learn more about how the coronavirus mutates, including those that can give rise to variants of concern,” says Cunha.

The study patient was infected with the strain B.1.1.28, which entered Brazil in early 2020. The researchers did not find mutations in the virus isolated from the patient that characterized them as a variant that is more transmissible or more resistant to the immune system.

These and other cases continue to be investigated by the Pasteur-USP Scientific Platform team. The 38 patients analyzed for this study are part of a bank of blood samples and nasopharyngeal secretions collected from 721 people who had symptoms related to the virus.

“New data will emerge from this sampling and we will possibly have more tangible explanations regarding these atypical situations”, estimates Cunha.

“These cases are further evidence that the best way to control the new coronavirus is by wearing a mask and avoiding crowds. If after 14 days of the positive test the individual is not tested again, he may still have active virus and be able to infect others, contributing to community transmission. Monitoring the infected is essential for a better understanding of mutations, new variants and the transmission capacity of SARS-CoV-2”, warns Minoprio.

About Jenni Smith

She's our PC girl, so anything is up to her. She is also responsible for the videos of Play Crazy Game, as well as giving a leg in the news.

Check Also

Dive confirms the first death from dengue in the state; victim was a resident of Criciúma

The Directorate of Epidemiological Surveillance of Santa Catarina confirmed the death of a 40-year-old man, …