H3N2 flu: All you need to know about the influenza virus and why people with respiratory disease need to be careful

Even though people get sick during this time of the year due to the winter and subsequent change in seasons, the H3N2 flu is turning out to be troubling as more people suffer from cold, cough and sore throat around the country. The Indian Council of Medical Research (ICMR) has not only said that the variant is more severe than all its other subtypes but also that patients should avoid the indiscriminate use of antibiotics or any other medication without consulting a doctor.

Dr Aniket Mule, consultant internal medicine, Wockhardt Hospitals in Mira Road explains, "Changing weather is the reason behind increased cases. The number of cases usually surge during the transitional phase of the season, due to low immunity.

"It causes respiratory distress and spreads through respiratory droplets when an infected person talks, coughs, or sneezes. Being highly contagious, it can easily spread from person to person," adds Dr Harshad Limaye, senior consultant, infectious diseases, Nanavati Max Super Speciality Hospital.

Mid-day Online spoke to Mule and Limaye to understand more about the influenza virus that is doing the rounds. The two city doctors say people need to take it seriously and visit a doctor as soon as they have common flu symptoms. They also highlight why people need to wash their hands and wear masks to prevent it.

What is the H3N2 flu and how is it caused?
Mule: H3N2 influenza, also known as the "Hong Kong flu," is a type of influenza A virus leading to respiratory illness.

Limaye: H3N2 is a type of influenza A virus, popularly known as the common flu in India. It causes respiratory distress and spreads through respiratory droplets when an infected person talks, coughs, or sneezes. Being highly contagious, it can easily spread from person to person. The virus can mutate quickly, which makes it difficult to develop an effective vaccine against it.

What are the other subtypes of the H3N2 flu? How is it different from the regular flu?
Mule: From the four that are A, B, C, and D influenza viruses, A and B lead to flu and respiratory illness that happens every year. But influenza subtypes such as H1N1 that is Swine Flu and H3N2 can lead to serious outcomes.

Limaye: The most prevalent subtype of Influenza A virus in India is H1N1, commonly known as Swine Flu. Other subtypes from influenza A family include H2N2, H5N1, H7N9, and H9N2. H3N2 is different from its fellow subtypes in genetic makeup, antigenic properties, and seasonal prevalence in India. It mutates more rapidly than other influenza viruses, and hence it's difficult to develop effective vaccines or treatments against the virus.

Why are many people suffering from it during this time of the year? When does it usually occur?
Mule: Changing weather is the reason behind increased cases. The number of cases usually surge during the transitional phase of the season, due to low immunity.

Limaye: The H3N2 or common flu usually spreads during winter months, between December and February, similar to all respiratory diseases. In India, it spreads easily from person to person due to densely packed urban areas and overall lack of general hand hygiene or masking protocols. The colder climate and low humidity during the season further contribute to the spread of the virus.

Which age group or group of people are most susceptible to the flu?
Mule: It is seen commonly in people above 50 and below the age of 13 years. Air pollution can also be one of the triggering factors for this.

Limaye: While everyone is susceptible to the flu, individuals with existing respiratory disorders such as asthma and bronchitis, immunocompromising conditions, lifestyle comorbidities such as heart disease or diabetes, children, and senior citizens are most at risk of developing severe infections that may require hospitalisation.

What are the symptoms of the H3N2 flu?
Mule: The symptoms of it are cough, nausea, vomiting, sore throat, fever, body ache, and diarrhoea. Moreover, people tend to develop upper respiratory infections such as pneumonia along with fever. Some people may also have seizures.

Limaye: At present, most patients with H3N2 are experiencing symptoms such as sore throat, persistent dry cough, high-grade fever which can go up to 102 degrees Fahrenheit. Some patients may also experience nausea, vomiting, and diarrhoea.

The ICMR has said there have been more hospitalisations through it than its other subtypes. Why should people be concerned about the H3N2 flu?
Mule: H3N2 influenza is contagious and spreads from person to person via droplets when an infected person talks, coughs, or sneezes. It can also spread by touching contaminated surfaces. Pregnant women, young children, older adults, and people with comorbidities are at a higher risk of suffering from it. One can also feel breathless and require hospital admission.

Limaye: While the condition is not alarming, as most patients are recovering within two days of starting Tamiflu, the symptoms of the virus do overlap with those of Covid-19, which is adding to the anxiety of patients. We urge individuals not to panic and seek treatment immediately after the onset of symptoms.

Is your hospital currently seeing more people come in for treatment for the flu? How many cases has Mumbai seen till now?
Mule: Almost 40-60 per cent of new patients coming to OPD have viral upper respiratory tract infection.

Limaye: There is no data on the city level since H3N2 is not a notifiable disease, but we have observed an increase in the number of flu patients coming to Nanavati Max Super Specialty Hospital. Each day, we see around 12-13 patients with similar symptoms of persistent dry cough, throat pain, cold, and high-grade fever, testing positive for H3N2. Most of these patients are young working individuals, which indicates that the disease is spreading through crowded areas such as trains, cinema halls, or markets.

When should people visit the doctor and can the H3N2 flu be treated?
Mule: One should immediately visit the doctor after having symptoms such as a cold, cough, fever, headache, runny and stuffy nose, and sore throat. The treatment will include antibiotics.

Limaye: People should visit a doctor immediately after the onset of symptoms, especially individuals with pre-existing respiratory disorders such as asthma and bronchitis, immunocompromising conditions, lifestyle comorbidities such as heart disease or diabetes, children, and senior citizens. They should not delay seeking professional advice before starting any Over-The-Counter self-medication or home remedies. Additionally, if you are experiencing any symptoms, ensure you wear masks and maintain hand hygiene to break the chain of infection.

Are people who have suffered from Covid at a greater risk of being affected by it?
Mule: Those with Covid will have compromised immunity which can make them susceptible to H3N2 flu. It is the need of the hour for everyone to take enough precautions and stay healthy.

Limaye: It is unclear whether people who have suffered from Covid-19 are at a greater risk of being affected by the H3N2 flu. However, people with underlying health conditions or weakened immune systems, which may have resulted from Covid-19 infections, may be at a higher risk of developing complications from both viruses.

Can the H3N2 flu be prevented? Does wearing masks help?
Mule: To prevent H3N2, wear a mask, avoid being around sick people, maintain a safe distance from people, wash hands from time to time, and do not touch contaminated surfaces such as doorknobs, handles, or furniture.

Limaye: Getting the flu vaccine shot can increase your protective levels against H3N2 infection. Gold preventive standards of any respiratory illness, such as regularly washing hands, wearing a mask, and avoiding crowded areas when sick, also apply to the flu. A simple triple-layer surgical mask also acts as a protective barrier, preventing infected droplets from spreading from one person to another. Therefore, it is essential to wear masks to prevent H3N2 infection.

Are there any certain types of food that can be consumed to prevent or deal with the flu?
Mule: One should have fresh fruits and vegetables to boost immunity, drink enough water to flush out toxins from the body, and drink soups to soothe the throat. If your tummy is upset because of diarrhoea then stick with bland foods. Oranges, lemons, and grapefruits are loaded with flavonoids and vitamin C known to reduce inflammation and boost immunity by tackling fever. Avoid spicy, oily, canned, processed, and junk food that can lead to inflammation in the body. Cut down on smoking and alcohol as well.

Limaye: There is no specific type of food that can prevent or cure H3N2 flu. However, a healthy and balanced diet can help support the immune system, which can potentially reduce the severity of the illness and help the body fight off the virus. Eating a variety of fruits and vegetables, lean protein sources, whole grains, and healthy fats can provide the body with essential nutrients to support immune function.

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