What is H3N2 flu, spreading across Delhi-NCR? Symptoms, diagnosis and treatment here

Complaints of fever, cough, itchy throat, and flu-like symptoms have ignited discussions around the H3N2 flu. According to a recent study conducted by LocalCircles, in the past 10 days, percentage of Delhi NCR households with one or more individuals experiencing viral illnesses dropped to 56%. They primarity experienced symptoms such as high fever, cough, sore throat, and fatigue, primarily attributed to H3N2.

Just 10 days back, the percentage of Delhi NCR households with one or more individuals experiencing viral illnesses was 69%, the survey said.

Let's find out what it is, how it spreads, and what its symptoms are. Later, we will clarify its diagnosis and treatment.

What is H3N2 flu?

According to Apollo Hospitals, it is a respiratory viral infection that primarily affects people over 50 and under 15. A subtype of the Influenza A virus, H3N2, is characterised by surface proteins hemagglutinin (H3) and neuraminidase (N2). These surface proteins mutate frequently, making immunity vulnerable and reducing the effectiveness of vaccination.

How does H3N2 virus prey on its host?

H3N2 flu is communicable, and people in closed spaces living in close proximity to the infected person are more at risk of catching the infection. It spreads primarily through respiratory droplets released during coughing, sneezing, or talking. One can also catch the infection by coming in contact with contaminated surfaces.

Individuals who haven’t been exposed to the virus before or whose immune systems are weak are more susceptible to catching the H3N2 flu, especially children, the elderly, pregnant women, and those with chronic conditions such as diabetes, asthma, heart disease, or other chronic ailments.

Gangaram Hospital Dr Atul Kakar said, “This virus in not new, it's an old virus. A special strain of this virus is spreading nowadays. This strain spreads when there is a change in the weather. Normally, symptoms are like an ordinary cough and cold, but some people have breathing difficulty and high fever. In some cases, patients are hospitalised, but in the majority of cases, this virus is self-limiting. People generally recover in 3-5 days,” PTI reported.

Crowded living conditions in schools, nursing homes and prisons are the hot spots where this contagious infection can be transmitted easily.

Symptoms of H3N2 flu

H3N2 infection symptoms typically begin with sudden high fever, chills, sore throat, headaches, muscle, body aches, fatigue, abdominal pain and sometimes gastrointestinal symptoms like nausea and diarrhoea.

Diagnosis of H3N2 flu

Though most cases are diagnosed clinically, the H2N3 virus can be detected through culture, throat swabs, rapid influenza diagnostic tests, and antibody tests.

Treatment of H3N2 flu

Although high-risk groups may require hospitalisation, the majority can recover at home with supportive care, including rest and hydration. Antiviral drugs like oseltamivir in early stages may be necessary in some cases, only after the recommendation of medical experts. Warm saline gargles and steam inhalation can provide relief in case of throat discomfort.

Gastroenterology Dr Aditya Gudheniya, in a post on X, stated, “Oseltamivir works against H3N2 by blocking virus release (neuraminidase inhibitor). If started within 48 hours of symptoms onset, it cuts illness by 1–2 days and lowers risk of severe disease/complications (especially in high-risk groups like the elderly, pregnant women, immunocompromised, or those with comorbidities).”

According to the Indian Council of Medical Research (ICMR) recommendation, physicians must treat H3N2 influenza primarily with symptomatic treatment rather than antibiotics.