A group of Brazilian scientists study the case of a patient who gave positive for coronavirus in PCR test for 218 days, a period in which the virus replicated and even mutated, academic sources reported this Wednesday.
This is a man in his 40s who, before suffering from COVID-19, had undergone aggressive cancer treatment, which had left his immune system quite weakened, according to a note by the Foundation of Amparo to the Investigation of the State of Sao Paulo (FAPESP).
The patient tested positive for the disease from September 2020 to April this year.
The research, published on the medRxiv platform and which has yet to be reviewed by other experts, was conducted by scientists from the University of Sao Paulo (USP), who discovered that the virus was not only present in the patient’s body, but also replicated for much of that time.
“During this entire period there was a risk of transmission for other people,” explained María Mendes-Correa, professor at the USP School of Medicine and first author of the research.
This was corroborated in in vitro examinations from weekly nasopharyngeal and saliva samples, and in which, after a few hours, it was possible to appreciate an increase in viral load.
“This replication capacity of the virus was observed continuously and persistently for a period of 196 consecutive days,” indicated Mendes-Correa.
Between January and April of this year, they also collected blood, urine and anal region samples, which also indicated the persistence of SARS-CoV-2 throughout much of the study period.
On the other hand, serological tests revealed that at no time did the patient develop antibodies.
In addition, the scientists also detected mutations of the pathogen throughout the infection process, from the genetic sequencing of nasopharyngeal samples collected on days 77, 134, 169 and 196 after the onset of the first symptoms.
Some of those mutations occurred in the ‘spike’ protein (spike), which the virus uses to penetrate human cells.
“The data suggest” that this evolutionary process of the virus “has occurred within the same host, when normally” these changes “are observed in community,” said Mendes-Correa.
“This is a worrying phenomenon, since it favors the emergence of viral variants better adapted to the human organism,” he added.
The patient in question remained a good part of the time admitted to the hospital and in the short periods of time in which he was at home, he also remained isolated.
With 505 thousand deaths and more than 18 million positives, Brazil is the Latin American country hardest hit by the coronavirus pandemic, the second in the world with the most deaths linked to the disease and the third with the most infections, behind the United States and India.