Researchers from the Pasteur-USP Scientific Platform (PCPU) followed an atypical case of Covid-19 infection: a 38-year-old man, who presented mild symptoms of coronavirus for 20 days, remained for 232 days with the virus being detected in the body and mutating . The results were published in the journal Frontiers in Medicine.
The rare case of SARS-CoV-2 infection is part of a group of 38 patients followed up weekly.
The patient was kept in social distancing and continued to wear a mask. Otherwise, he could have spread the pathogen for more than seven months.
Patients were followed until two or three consecutive RT-PCR tests were negative.
The study, supported by FAPESP, warns about the risk of releasing patients with Covid-19 after seven, ten or even 14 days of the positive test — as predicted in the initial protocols to combat the coronavirus.
Marielton dos Passos Cunha, first author of the study, carried out during a postdoctoral internship at PCPU, explains that of the 38 cases 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 be able to transmit the virus for more than two months, without necessarily showing any symptoms during the final phase of infection.”
Virus remains in the body
The researchers wanted to know if 14 days was really enough for the virus to stop being detectable.
“We found that not. On average, it can take a month for the test to be negative and, in some cases in this study, the positivity lasted from 71 to 232 days”, says Paola Minoprio, one of the coordinators of PCPU and leader of the study.
This is not the first time that patients with mild symptoms have been active in the body for longer than expected.
In 2021, researchers at the Institute of Tropical Medicine at the University of São Paulo (IMT-USP) analyzed 29 samples from people who tested positive for Covid-19.
The material was collected at a Basic Health Unit (UBS) 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. 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.
mutations in the virus
In the study led by Minoprio, there were three atypical cases: a woman remained 71 days with the detectable virus, and a man, 81 days – in addition to the third patient, a male, remained 232 days with a positive diagnosis for the virus.
In the former, patients did not have any comorbidity. Despite this, the patient who spent 232 days with the tivo virus has been carrying HIV, the virus that causes AIDS, since 2018, but maintains an undetectable viral load with treatment.
Minoprio said that being HIV positive does not mean 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 anyone else’s, so much so that he responded to the coronavirus from the very beginning of the infection. This is not an immunosuppressed individual. [como pessoas em tratamentos de câncer, doenças autoimunes ou transplantados, por exemplo]”He says.
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 but of mutation.
The scientists explain that during the infection, they could 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.
Cunha points out that it is important to observe patients like this one because researchers can learn more about how the coronavirus mutates, including those that can give rise to variants of concern.
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.
Minoprio says these cases are further evidence that the best way to control the new coronavirus is to wear a mask and avoid crowds.
“If after 14 days of the positive test the individual is not tested again, he may still have active viruses and be able to infect others, contributing to community transmission”, he warns.
Reduction in isolation time in Brazil
The Ministry of Health announced this week the reduction of isolation time from ten to seven days for people with mild to moderate symptoms.
The guidance of the folder is that the isolation should be done as long as the person has not had respiratory symptoms and fever for at least 24 hours – without the use of antipyretics.
At the end of 2021, the Centers for Disease Control (CDC), in the United States, 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.
*With information from André Julião, from Agência FAPESP
Reference: CNN Brasil
