A group of international researchers discovered that the novel coronavirus can remain in some human bodies for up to 232 days.
A study involving 38 Brazilian patients was conducted by researchers from France’s Pasteur Institute, the University of Sao Paulo (USP), and the Oswaldo Cruz Foundation (Fiocruz) in Brazil.
The patients were followed until they tested negative for RT-PCR twice or three times in a row.
The findings, published in the journal Frontiers in Medicine, revealed that two men and a woman were atypical in the sense that the virus was continuously detected in their organism for more than 70 days.
“Based on this result, we can say that about 8 per cent of people infected by SARS-CoV-2 may be able to transmit the virus for more than two months, without necessarily manifesting any symptoms during the final stage of the infection,” said Marielton dos Passos Cunha, first author of the article.
The novel coronavirus remained detectable in the body of a 38-year-old man who had mild Covid-19 symptoms for 20 days and was undergoing mutations for 232 days, according to the researchers.
“If he had not been given continuous medical care, maintained social distancing and worn a mask, he could have spread the virus throughout these seven months,” they added.
“We wanted to know if a period of 14 days was really long enough for the virus to stop being detectable. We concluded that it wasn’t. It can take a month for a patient to test negative, and in some cases included in our study the patients remained positive for 71 to 232 days,” said Paola Minoprio, principal investigator for the study.
This isn’t the first time the virus has been found to be active for longer than expected, even in patients with mild symptoms.
Researchers at the University of Sao Paulo’s Institute of Tropical Medicine (IMT-USP) in Brazil examined 29 samples of nasopharyngeal secretion from patients who tested positive for Covid-19 in early 2021.
The viruses present in the samples were capable of infecting and replicating in vitro in 25% of the cases.
Researchers from the same university’s Medical School (FM-USP) described a case of infection that lasted at least 218 days in a paper published in June 2021.
Before contracting Covid-19, the patient was about 40 years old and had undergone aggressive cancer treatment.
Another study published in the New England Journal of Medicine in early December 2020 described the case of a 45-year-old immunocompromised man with an autoimmune blood disorder in whom the virus replicated for 143 days. In late December, Cell published a case study of a female leukaemia patient in whom the virus replicated for at least 70 days despite the fact that she had no symptoms of Covid-19.
“If 14 days after testing positive, a person isn’t tested again, they may still be shedding active viruses and be able to infect others, contributing to community transmission,” Minoprio said.
“It’s crucial to keep track of infected people so we can find out more about mutations, novel variants, and the transmissibility of SARS-CoV-2.”