
The identification of a new type of influenza A (H3N2) virus, known as the “K virus,” in Brazil is not yet a cause for concern, says Renato Kfouri, vice-president of the Brazilian Society of Immunizations (SBIm).


The circulation of influenza strains is part of the natural dynamics of the virus, and at this point, there is not enough information to predict a major impact on the upcoming flu season, he noted. Any estimates regarding the severity, duration, or intensity of the upcoming season would be premature.
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“We don’t know if this will be the predominant strain circulating worldwide. The season is just beginning in the Northern Hemisphere. We don’t even know if it will be the H3N2 season or if another H1N1 will come. It’s all still very theoretical,” said Kfouri.
Last week, the World Health Organization (WHO) issued an information note drawing attention to the rapid increase in the circulation of the K variant of influenza A in the Northern Hemisphere – particularly in Europe, North America, and East Asia.
In Europe, influenza activity started earlier than usual. The K variant accounted for almost half of the cases of infections reported from May to November this year. No significant change in clinical severity has been reported yet in terms of hospitalizations, intensive care admissions, or deaths.
Registration
This week, the Brazilian Ministry of Health published a report on the epidemiological situation in the country and mentioned for the first time the identification of a case of the K variant in Brazil, in the northern state of Pará.
On Wednesday (17), the research institute Fiocruz provided more details about the registration. The sample containing the new strain was collected in Belém, capital of Pará, on November 26 and was first analyzed there.
After confirmation of influenza A (H3N2), the material was sent to Fiocruz, where it underwent genetic sequencing.
The case involved an adult patient, a woman from Fiji, and was classified as imported. To date, there is no evidence of local transmission associated with the variant in Brazil.
The detection of new variants is expected, Kfouri pointed out.
“Every year we have new influenza strains. It is in the nature of the virus to mutate and cause annual epidemics. That is why we need to get vaccinated every year. Vaccines are updated according to what can be predicted will circulate in the following season,” he stated.
Vaccine
Fiocruz experts emphasize that vaccination remains the main prevention tool. The composition of the inoculation recommended by the WHO was updated in September, with strains closer to those currently in circulation, including the K subclade.
“The composition of the influenza vaccine recommended by the World Health Organization was updated in September for next year, with strains closer to those currently in circulation, including the K subclade,” says Marilda Siqueira, laboratory head at Fiocruz.