A group of Brazilian scientists is studying a case of infection by the new coronavirus that lasted at least 218 days with the virus replicating and mutating during this period. The team describes the phenomenon as “worrying” as it points to the emergence of variants that are more adaptable to the human organism.
The research was conducted by scientists from the University of São Paulo (USP) with the support of the Foundation for Research Support of the State of São Paulo (FAPESP), and published this week on the MedRxiv platform to publicize the case. The review has not yet gone through the peer review process.
The patient in question, a 40-year-old man, tested positive for the disease between September 2020 and April this year. Before being diagnosed with covid-19, the patient had undergone aggressive cancer treatment, which had left his immune system severely weakened.
“During this entire period, there was a risk of transmission to other people,” explained María Mendes-Correa, a professor at the Faculty of Medicine at USP and the first author of the study. The situation was corroborated in in vitro exams from nasopharyngeal and saliva samples extracted weekly, in which, after a few hours, it was possible to verify an increase in the viral load.
“This ability to replicate the virus was observed continuously and persistently for a period of 196 consecutive days”, out of a total of 218 days of infection, indicated María Mendes-Correa.
Between January and April of this year, blood, urine and anal samples were also collected, which also indicated the persistence of SARS-CoV-2 throughout much of the study period. On the other hand, serological tests revealed that the patient never developed antibodies.
Scientists also detected pathogen mutations during 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 these mutations have occurred in the spike protein, which the virus uses to penetrate human cells.
María Mendes-Correa explains that the data suggest that the evolution of the virus “occurred within the same host” when, as a rule, these changes “are observed in the community”.
“This is a worrying phenomenon, as it favors the emergence of viral variants that are more adapted to the human organism”, added the researcher. The patient in question spent much of the time in the hospital and remained isolated during the short periods he remained at home.