H3N2 Flu Cases On Rise: Symptoms, Severity, Testing & Tips To Stay Safe


Various parts of India have observed a sharp increase in aggressive and prolonged flu cases. Presenting with COVID-like symptoms including a persistent cough, fever, cold, body aches, diarrhea, vomiting, etc., flu is worse than the common cold and symptoms begin more abruptly.

As per the surveillance data by the ICMR (Indian Council of Medical Research) from December 15th 2022 till date, H3N2 flu is the main cause behind this surge.[1] About half of all inpatient severe acute respiratory illness (SARI) and outpatient flu-like illnesses were found to have H3N2. The World Health Organization (WHO) case definition of severe acute respiratory infections (SARI) is anyone with acute respiratory infection with symptoms within 10 days of presentation, cough, fever, and hospitalization.

Flu (influenza) viruses can fall under four broad types: influenza A, B, C or D.

Influenza A is the most common type. Influenza A can further have subtypes. H3N2 is a subtype of the Influenza A virus.

H3N2 can be more concerning than other flu viruses

This subtype appears-

-To cause more hospitalizations than other influenza subtypes[2]
-With symptoms like high fever, breathlessness, wheezing, coughing, clinical signs of pneumonia and seizures in hospitalized people. [2] A few needed oxygen and ICU care too.
-To be more severe than other influenza subtypes in terms of fever as per a few studies.[3]

The data further revealed that in patients affected by influenza A H3N2, around 92% of people are suffering from high fever, 86% from a severe cough and 27% from shortness of breath, 16% from clinical signs of pneumonia and another 16% from wheezing. Moreover, in rare cases, 6% of patients exhibit seizures that require urgent medical intervention.[2] ICMR further stated that 10% of people with SARI due to H3N2 needed oxygen, and 7% had to be given ICU care.

How can one catch H3N2?

The H3N2 virus is quite contagious. Similar to COVID and other flu viruses, it is a respiratory germ and transmits from one person to another through droplets released when coughing, sneezing, or talking by an infected person. It can also spread if someone touches their mouth or nose after contacting a surface that has the virus on it. Once infected, it can usually last 5-7 days. Fever may go at the end of 3 days but cough and throat discomfort can persist for up to 3 weeks.

While colds, COVID, and flu have many symptoms in common, your doctor may need some special tests to tell what is causing the fever or respiratory sickness in your case.
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*This package provides a complete flu screening by testing for both Influenza A and Influenza B viruses. The technique of testing is PCR (similar to COVID), hence a swab sample will be required.

6 simple steps to stay safe from H3N2-

1. Maintain hand hygiene & mask up
Wash your hands often with soap and water. Wear your mask and avoid crowded, poorly ventilated places, especially if you have flu-like symptoms.

From medicines to masks, from tests to hygiene supplies, get your flu care delivered to your home.
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2. Get your flu shot
An annual flu shot is a simple way to prevent getting severe flu. You need to get vaccinated every year. Since flu viruses change so quickly, last year’s vaccine may not protect you from the currently circulating viruses.

Consult your doctor and schedule your vaccination.
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3. Care for the special people in a special way
A statement from the IMA (Indian Medical Association) stated that it mostly occurs in people above 50 years and children below 15 years. Young kids, pregnant women, the elderly, and people with chronic medical conditions like diabetes, kidney disease, heart disease, lung disease, cancer, etc., can have an increased risk of developing more serious flu complications, such as pneumonia, ear infections, etc.

If the symptoms persist for more than 3 days or worsen, do seek a medical opinion. Do not keep self-medicating at home.

4. Do not take antibiotics unless prescribed
They work against bacteria, not viruses. In most cases, a symptomatic approach to treatment suffices. Fever and aches can be relieved with paracetamol. Medicine for cold and coughs may also be needed. Antiviral medicines are given to people at risk for more serious symptoms.

Take medicines only as prescribed by your doctor. Misuse of antibiotics can lead to antibiotic resistance. That may cause them to be ineffective when really needed.
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 5. Rest and hydrate
Drink lots of liquids to prevent dehydration. Take adequate rest. Get enough sleep. Stay home until you feel better. Some kids need to stay home longer.

6. Keep your near and dear ones at a safe distance
If you are sick, take care to not spread the infection further. Do not share personal items and food. Avoid contact greetings like handshakes and high five. Never spit in public. Avoid sitting close to others in public places. You can consider that you are not contagious only when you haven’t had symptoms for at least 24 hours.

Quick reminder
Air pollution can also be a precipitating factor for serious flu infection. Experts say air pollutants can even make symptoms of the flu feel worse for those who are already sick.

Been exposed to high pollution continuously? Check for its effects with a simple blood test.
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Take home message
Make sure to seek an expert opinion and get special tests, if you have a respiratory illness, high fever, or flu-like symptoms. Watch out for the symptoms. Most importantly, do not pop antibiotics just like that, or stop before the course ends when you feel better! These are life-saving medicines that must be judiciously used under a doctor’s supervision. If you haven’t got your flu vaccine yet, get vaccinated. Stay aware, and stay safe!

(The article is written by Dr. Swati Mishra, Medical Editor, and reviewed by Dr. Rajeev Sharma, Vice President (Medical Affairs))


1. https://pib.gov.in/PressReleasePage.aspx?PRID=1905602; https://twitter.com/ANI/status/1631677691987480579/photo/1
2. MoHFW. https://www.instagram.com/p/Cpm1pRxIRAd/?igshid=MDJmNzVkMjY%3D
3. Kaji M, Watanabe A, Aizawa H. Differences in clinical features between influenza A H1N1, A H3N2, and B in adult patients. Respirology.

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