New COVID-19 variant detected in Rio de Janeiro
The Oswaldo Cruz Institute (IOC), part of the Oswaldo Cruz Foundation (Fiocruz), has confirmed that a new XFG variant of the SARS-CoV-2 virus, which causes COVID-19, is circulating in the municipality of Rio de Janeiro.
The viral genomes were sequenced by the institute’s laboratory, which serves as a reference center for the Ministry of Health and the World Health Organization (WHO).
Through a surveillance strategy established in partnership with the Rio de Janeiro Municipal Health Department, the strain was identified in 46 COVID-19 cases diagnosed between July 1 and 8, accounting for 62 percent of the genomes analyzed during that period.
Rio de Janeiro is the fourth Brazilian state to report the strain, after São Paulo (2 cases), Ceará (6), and Santa Catarina (3).
First detected in Southeast Asia, the XFG strain has spread rapidly across several countries. On June 25 of this year, the World Health Organization (WHO) classified it as a “variant under monitoring.” The designation was made by the WHO’s Technical Advisory Group on Virus Evolution, which includes virologist Paola Resende from the Fiocruz laboratory.
The XFG variant has genetic mutations and has been detected more frequently in several countries in recent months. However, there are no signs that it causes more severe disease or significantly affects the effectiveness of vaccines and antivirals.
Given the situation, the WHO advisory group assessed the risk associated with the strain as low and emphasized the need to strengthen surveillance. “However, there is no evidence of increased clinical severity or any significant impact on the effectiveness of vaccines and antivirals. That’s why our decision, as the WHO technical group, was to classify the strain as a variant under monitoring—it requires closer observation to detect any potential changes in its behavior,” said Paola Resende.
In Rio de Janeiro, the surveillance strategy adopted in partnership with the Municipal Health Department expanded sample collection for genetic sequencing following a slight increase in COVID-19 cases diagnosed through rapid tests at basic health units.
