As a new strain of influenza makes its way around the world, healthcare professionals are highlighting important symptoms to be aware of as flu season kicks off.
This updated version of influenza A H3N2 appeared earlier this year and has led to a significant number of hospitalizations in countries such as Japan, Australia, and the UK, impacting thousands with its unusually severe symptoms.
In the United States, flu is a common occurrence, but this new variant is turning out to be particularly contagious and severe. This is mainly because it has undergone several mutations that render this year’s flu vaccines, which were developed for a different influenza strain, less effective.
The mutated H3N2 strain, known as ‘subclade K’, has quickly spread worldwide. Japan declared it an epidemic, encountering an unusually early and intense flu season this year.
There were nearly 200,000 cases reported in Japan between November 17 and November 23. Consequently, multiple schools temporarily closed to help control the spread of the infection.
These closures were not akin to the full-scale lockdowns seen during the pandemic but were short-term measures intended to slow the transmission of the virus.
The United Kingdom is also bracing itself for what could be the ‘worst flu season’ in over ten years, while Canada is observing high infection rates as well.
In the United States, H3N2 subclade K has been found in more than half of the states. Experts are cautioning that it might be particularly dangerous for older adults and children.
“Knowing that there’s a new mutated strain out there and H3N2 generally causes more severe disease is concerning,” Dr. Robert Hopkins Jr., medical director of the National Foundation for Infectious Diseases, explained to TODAY.com.
According to the U.S. Centers for Disease Control and Prevention, the peak flu season usually occurs between December and February, although it can extend into May.
In the U.S., four types of Influenza exist: A, B, C, and D.
The most prevalent types are Influenza A (including strains like H1N1 and H3N2) and Influenza B. This year’s flu vaccine was designed to target these types.
However, H3N2 has undergone mutations since the vaccine was formulated, resulting in a more aggressive strain that the current vaccines do not effectively target.
The H3N2 subclade K strain has acquired seven new mutations.
The symptoms associated with the mutated H3N2 flu strain are similar to those of the seasonal flu, including:
• Fever
• Chills
• Body aches
• Headache
• Extreme fatigue
• Congestion or runny nose
• Coughing
These symptoms can appear suddenly, sometimes overnight, and resemble those caused by COVID-19 and other viruses.
Influenza is generally a self-resolving illness that can be managed at home with adequate rest and hydration and typically resolves within five to seven days.
However, if symptoms are severe, or if there is a high fever, signs of dehydration, or difficulty breathing, it is crucial to seek medical advice.
“The flu is not just a cold. It can be quite severe,” Hopkins emphasized.
In the 2023-2024 flu season, approximately 28,000 people in the US died from the flu, with around 470,000 being hospitalized.