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Preventive Healthcare

H3N2 Flu: Symptoms, Treatment, Outlook & Prevention



With a change in the weather and climate, cold, flu and fever are the first to arrive. One flu that has been widely spoken about recently is H3N2. Influenza A H3N2 viruses were first detected in pigs over a decade ago.

Multiple sporadic outbreaks have occurred since then, but all were due to a pig-to-human transmission. It is the first time that a broader virus outbreak has been observed in several countries, including India.

A few reasons why H3N2 is spreading in India include low vaccination rates (for the flu vaccine) and high pollution. India has two peak seasons for the flu outbreak—between November and February and one during monsoons. Research so far states that H3N2 causes severe infection and illness in people over 65 years of age and children below 5 years. 

How Can You Catch H3N2 Flu?

H3N2 flu is contagious and spreads through droplet infections like COVID-19 and other seasonal flu. You can catch the virus by coming in contact with an infected surface and touching your face, eyes or mouth immediately after. You can also develop the infection when you come in close contact with an infected person. Once your symptoms develop, they may last up to 5 or 7 days.

What Are The Symptoms of H3N2 Flu?

The symptoms of H3N2 flu are very similar to other seasonal flu and include:

  • Runny or stuffy nose
  • Sore throat with cough
  • Headache
  • Fever
  • Chills
  • Body ache
  • Fatigue
  • Diarrhoea
  • Vomiting

How is H3N2 Flu Diagnosed?

While most doctors can diagnose the H3N2 flu due to its common symptoms with other flu, they may recommend patients undergo lab tests to rule out any other illnesses common during the season.

How is H3N2 Flu Treated?

The treatment for H3N2 flu depends upon the individual's symptoms and severity. Uncomplicated cases of H3N2 are treated like any other seasonal flu:

  • Getting plenty of rest
  • Drinking enough fluids (juice, soups, water) to stay hydrated
  • Taking over-the-counter medications to help relieve fever, headache and body pain

In some cases of H3N2, antivirals like oseltamivir, baloxavir and peramivir may be given. When antiviral medications are administered within 48 hours of developing flu symptoms, they can shorten the duration of the illness and prevent complications.

Seek immediate medical care if you fall under the following high-risk categories:

  • Adults over 65 years of age
  • Children under 5 years of age
  • Pregnant women
  • Individuals with chronic medical conditions like diabetes, pneumonia, asthma, heart disease or weakened immune system

Is There A Vaccine For H3N2 Flu?

Flu vaccinations prevent severe diseases and symptoms in the general population. Unfortunately, there is no vaccine to prevent one from H3N2 flu specifically. The annual flu vaccine protects from three to four strains of the flu virus (hence they are called trivalent or quadrivalent).

However, these flu vaccines protect you more from the H1N1 viruses and influenza B viruses than the H3N2 viruses. This happens because the H3N2 viruses undergo more frequent genetic changes than the others, making the vaccine less effective against them.

What Is The Outlook of H3N2 Flu After Treatment?

Despite the rising cases of H3N2 flu, most people can recover at home with or without treatment from their physicians. The flu symptoms last for around a week or two but the cough and weakness may linger for a couple of weeks longer. 

If you belong to a high-risk group, you must visit your doctor as soon as flu symptoms set in. 

Symptoms that may require you to seek emergency care include:

  • Shortness of breath or difficulty in breathing
  • Pain or pressure in the chest
  • Dizziness or lightheadedness
  • Severe or persistent vomiting
  • Confusion
  • Worsening of existing symptoms

Can H3N2 Flu Be Prevented?

Though we still don’t have an H3N2-specific vaccine, we can still protect ourselves and our loved ones from this infection using the following steps:

  • Get the yearly flu shot, preferably before winter sets in.
  • Wash your hands frequently with soap and water, especially after using the washroom, before eating and touching your face, mouth and eyes.
  • Wear a mask when going out in a crowded area or a poorly ventilated indoor space.
  • Avoid crowded places during flu season where the infection can spread quickly.
  • Stay away from people who are sick.
  • Avoid taking antibiotics without your doctor’s prescription

If you are sick with the H3N2 flu, avoid heading out in public to prevent the spread of the infection. It is recommended to stay home for at least 24 hours after the fever has subsided.


H3N2 flu is a serious viral infection that can cause significant morbidity and mortality, particularly in vulnerable populations like the elderly and young children. Since there is no vaccination for H3N2, the best way to prevent the flu and its complications is to use preventative measures, like frequent hand washing and avoiding contact with infected individuals.

You can test yourself to see if you are infected with the H3N2 virus. Metropolis Lab's Flu-Xpert Viral Panel uses the real-time Multiplex PCR method to detect 5 strains of flu including Influenza A, Influenza B, H1N1, H3N2 and RSV (Respiratory syncytial virus). It requires only a one-time sample collection and results will be made available within 12 hours. Schedule your test now!

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