A new, potentially virulent strain of influenza A, designated H3N2 subclade K, is gaining traction in the Northern Hemisphere, triggering concerns about its eventual arrival in South America. Already detected in Mexico and Peru, the variant has overwhelmed healthcare systems in parts of Europe and is prompting Argentinian health officials to prepare for a possible surge in cases this summer. Experts stress the importance of vaccination, though current coverage rates are lagging, leaving the population vulnerable as the virus continues to evolve [[1]].
The flu vaccine is the main preventative measure, recommended for travelers / demian alday
A new variant of the influenza A virus, the H3N2 strain, is causing concern as it spreads through countries in the Northern Hemisphere heading into winter. The mutation, known as type “K,” first emerged in Oceania in August and has since reached Europe, arriving weeks earlier than usual and overwhelming healthcare systems in places like England and Spain.
The emergence of crowded hospital wards and patients being treated in hallways has prompted a familiar question: could this strain reach Argentina, and specifically, La Plata? And if so, what steps should be taken?
Local infectious disease specialist Silvia González Ayala told reporters that cases have already been detected in Mexico and Peru. “It is inevitable that it will arrive in the country, especially because of the high volume of tourists traveling between the Northern and Southern Hemispheres. It will happen sooner rather than later,” she said. However, she added that because it is currently summer in Argentina, the country has a potential advantage. “If the virus enters, it will cause flu cases that are indistinguishable from those caused by other strains.” She also suggested the virus may already be present in Argentina, even in Buenos Aires, but has not yet been detected, requiring testing to confirm cases.
González Ayala explained that if the virus does establish itself in Argentina, there will likely be an increase in flu cases and potentially more hospitalizations. “Our healthcare system will respond, despite being significantly strained,” she noted.
According to the latest National Epidemiological Bulletin, which analyzed data up to December 6, the “genetic subclade K has been detected in more than 34 countries,” but as of early November, it had not been identified in South America. This information is crucial for monitoring the spread of the virus and preparing public health responses.
The Vaccine
While the invading strain is new, the 2025 flu vaccine – the same one used in the Northern Hemisphere – offers partial protection, particularly against severe illness and hospitalization, González Ayala stated.
She recommended that individuals traveling to the Northern Hemisphere get vaccinated with the current flu vaccine 15 days before their trip. The National Epidemiological Bulletin echoed this advice, stating that “prevention and control measures, including vaccination, remain fundamental to reducing the burden of severe illness and hospitalizations associated with influenza.”
This call for vaccination comes at a time of low coverage – currently 20 percent below the necessary level. As a result, preventable diseases like measles and whooping cough have reemerged in recent months. The specialist also warned that the strain could mutate again, and the World Health Organization is already preparing a new vaccine for 2026. The potential for further mutations highlights the importance of ongoing surveillance and vaccine development.
