How To Treat Or Prevent H3N2 Flu? What Makes It More Deadly Than Other Influenza Strains? Here's What Experts Say

H3N2 infection mostly results in flu-related illnesses, but can also cause problems such as pneumonia, bronchitis, and ear infections, and aggravate pre-existing illnesses such as asthma.

H3N2 Infection: Along with medications, supportive care is important to manage the symptoms caused by H3N2 infection. This means that the person should get adequate rest and hydration.

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H3N2 flu cases in India are on the rise, with several children and people belonging to older age groups being hospitalised. H3N2 is a subtype of Influenza A virus, and has already claimed two lives in India.

Since the beginning of 2023, H3N2 has been the predominant subtype among the samples testing positive for influenza. Since Influenza A viruses are the only influenza viruses known to cause flu pandemics, and the symptoms of H3N2 flu are similar to those of Covid-19, people are worried if H3N2 is as deadly as SARS-CoV-2. 

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H3N2 appears to cause more hospitalisations than other influenza types, according to the Indian Council of Medical Research (ICMR). The common symptoms of H3N2 infection are fever, cough, breathlessness and wheezing, while pneumonia and seizures are rare symptoms. 

Medications to treat H3N2 flu

H3N2 flu can be treated through antiviral medications, which must be administered within two days of the onset of symptoms, experts say.

“Treatment for H3N2 flu typically involves antiviral medications such as oseltamivir or zanamivir. These are neuraminidase inhibitors approved by the Food and Drug Administration (FDA). Antiviral medications can help reduce the severity and duration of symptoms when taken within the first 48 hours of illness,” Dr Dipu TS, Associate Professor, Division of Infectious Diseases, Amrita Hospital, tells ABP Live.

Supportive care is also important to manage the symptoms caused by H3N2 infection. This means that the person should get adequate rest and hydration. The elderly and children, who are at higher risk of H3N2 infection than others, may need to be hospitalised.

“In addition to antiviral medications, supportive care such as rest, hydration, and fever-reducing medications can also be helpful in managing symptoms. People with H3N2 infection who are at high risk of complications, such as the elderly, young children, and those with underlying health conditions, may require hospitalisation and intensive treatment, such as supplemental oxygen if the disease is severe,” says Dr TS.

Peramivir and baloxavir are also some antiviral medications which can be used to treat H3N2 infection.

“The same influenza antiviral drugs used to treat seasonal flu can treat H3N2 infection in children and adults. Peramivir, and baloxavir are some drugs available by prescription from your doctor. However most patients require symptomatic treatment for fever and cough,” Dr. Yash Javeri, Director – Critical care and emergency medicine, Regency Hospital, tells ABP Live.

Some people infected with H3N2 may have to be treated with steroids.

“Antiviral medications must be started within two days of symptoms to have better outcomes. Some may require steroids and ventilator support,” Dr. Honey Savla, Internal Medicine, Wockhardt Hospitals, Mumbai Central, tells ABP Live.

How can H3N2 be prevented?

H3N2 infection can be prevented by wearing masks, avoiding crowded places, covering mouth and nose while sneezing and coughing, avoiding touching eyes and nose, especially after touching an external surface, drinking plenty of fluids, and taking paracetamol for fever and body ache. 

Also, people must avoid shaking hands, must not spit in public, should not eat together sitting close to others, and must not take antibiotics or other medicines without consulting a healthcare professional. 

Vaccination is the most effective way to prevent seasonal influenza infection. When the circulating viruses are well-matched with viruses contained in vaccines, an influenza vaccine is the most effective. 

A trivalent influenza vaccine includes two subtypes of Influenza A virus, and one Influenza B virus subtype. Quadrivalent vaccines include all these viruses, along with another Influenza B virus subtype. 

“Prevention measures, such as getting an annual flu vaccine, practising good hand hygiene, and avoiding close contact with sick individuals and wearing masks are important to reduce the spread of H3N2 and minimise the risk of infection,” says Dr TS.

According to the Centers for Disease Control and Prevention (CDC), flu vaccination reduces the risk of flu illness by 40 to 60 per cent in the overall population during seasons when most of the circulating flu viruses are well-matched to those used to make flu vaccines. However, current flu vaccines offer less protection against H3N2.

Why there has been a spike in H3N2 cases

Since January this year, there has been a 29 per cent increase in flu-related consultations, according to Practo insights. Practo is a healthcare platform.

“Similar to H1N1, H3N2 is a winter virus that never went away. A Practo insight reveals that there has been a 29 per cent spike in flu-related consultations since January and if you observe, the cases of flu have actually been on the rise since or even a little before that. The primary reason for the spike is due to lowered immunity. We had far less exposure to the winter virus during the last two winters due to Covid-19,” Dr Rajesh Bharadwaj, an ENT specialist who consults on Practo, tells ABP Live.

The lack of adequate flu vaccination and people crowding public places are some other reasons behind the spike in H3N2 cases.

What problems can H3N2 lead to, apart from flu-related illness?

While H3N2 infection mostly results in flu-related illnesses, the virus can also cause problems such as pneumonia, bronchitis, and ear infections, and aggravate pre-existing illnesses such as asthma and heart disease. The age of a person, their general health, and the presence of other comorbidities or illnesses determine whether they will have a mild or severe infection.

“In certain instances, H3N2 can cause problems like pneumonia, bronchitis, and ear infections. In addition to aggravating pre-existing illnesses such as asthma and heart disease, the virus may necessitate hospitalisation. H3N2 infections can range in intensity from mild to severe, depending on variables such as age, general health, and the presence of other illnesses,” says Dr TS.

What makes H3N2 more deadly than other influenza strains?

Since H3N2 tends to mutate more quickly, it is more difficult for flu vaccines to keep up with its mutations. This is what makes H3N2 more deadly than other influenza strains. Therefore, flu vaccines may be less effective against H3N2.

“H3N2 is regarded as more deadly than other influenza strains because it tends to mutate more quickly, making it more difficult for vaccines to keep up with its mutations. This can result in decreased H3N2 vaccine efficacy rates compared to other influenza viruses. The most effective strategy to prevent the flu, particularly H3N2, is to practise excellent hygiene, get vaccinated annually, and seek medical attention as soon as symptoms appear,” says Dr TS.