Understanding the H3N2 Virus: Impact and Spread in India

India is currently grappling with a surge of influenza infections, predominantly caused by a virulent strain known as H3N2. Given how quickly this viral outbreak spreads, people must recognise its prevalence rate and take the appropriate safety measures. According to the World Health Organization (WHO), the H3N2 strain is mostly to blame for influenza-related hospital admissions and fatalities worldwide.

This blog post will provide an in-depth look at the defining traits of the H3N2 influenza virus, its high incidence in India this flu season, and how it differs from other common flu strains.

H3N2 Virus: What Is It?

A non-human influenza virus called the H3N2 strain typically infects humans after circulating in pigs.

  • Influenza viruses can be divided into type A (H1N1, H3N2), type B (Yamagata, Victoria), type C, and type D.
  • Because influenza A-type viruses have the potential to spread worldwide, they pose a more significant threat to public health.
  • The subtypes of the influenza A virus are further divided based on the combinations of distinct neuraminidase (NA) and hemagglutinin (HA) virus surface proteins.
  • Influenza A viruses can be classified as swine, avian, or other types depending on the host source.
  • Animal type A viruses are not readily transmissible among humans and are entirely distinct from human influenza viruses.

A characteristic of the H3N2 strain is its higher mutation rate than other influenza viruses. These properties make the virus adapt, evading the host's immune response and leading to a more severe outbreak.

Prevalence Of H3N2 in India

H3N2 virus-induced influenza was more prevalent in 2017 and 2018. Seasonal flu dominated by H3N2 typically has higher case counts, primarily in high-risk populations such as younger children and older adults. With its large population and diverse climate, India faces a significant burden of influenza viruses every year.

Several factors, such as population density, healthcare infrastructure, and public awareness, influence India's spread of the H3N2 strain. Here is the list of prevalence rates linked to population:

  • The H3N2 virus is said to be the dominant strain of the virus this season, with the H3N2 positivity rate in the various states reaching 19 percent in Mumbai.
  • According to NIV, which is part of a national network of 32 laboratories that identify and study influenza viruses, the high prevalence of H3N2 could be due to the immune profile of the population.
  • Although both influenza A virus and B are responsible for outbreaks and seasonal epidemics, influenza A is the only one with pandemic potential.

According to the Ministry of Health, ICMR's network of laboratories regularly monitors human influenza viruses in patients with severe acute respiratory illness (SARS) and influenza-like illness (ILI). The trends seen earlier this year, from January 2 to March 5, clearly show that H3N2 is dominant and accounts for nearly 79% of all influenza viruses detectedImagein samples from patients with SARS or ILI.

Differences From Other Viruses

H3N2 strain differs from other viruses in many ways, contributing to its unique characteristics and effects. They are as follows:

  • H3N2 Vs H1N1 (Swine flu)

Influenza is an H3N2 infection more severe than an H1N1 or B illness regarding fever, leukopenia, and C-reactive protein. Although both strains can cause similar symptoms, H1N1 is associated with more severe respiratory symptoms, such as coughing and shortness of breath, and gastrointestinal symptoms, such as diarrhoea and vomiting. H3N2, on the other hand, can cause muscle aches and fever.

  • H3N2 Vs Influenza B

Generally, influenza B viruses evolve more slowly in genetic and antigenic characteristics than influenza A viruses, especially influenza A(H3N2) viruses. Common symptoms include a runny nose, sore throat, fever, chills, body aches, and fatigue. The main difference is hardness. Type A influenza symptoms are more severe than type B influenza.

  • H3N2 Vs SARS CoV-2 (Covid 19)

COVID-19 is caused by the SARS-CoV-2 virus, which is the H3N2 variant of the influenza virus. COVID-19 is more contagious than H3N2; symptoms can range from mild to severe. In addition, COVID-19 can cause loss of smell or taste, which is not a symptom of H3N2. Moreover, COVID-19 can cause more serious complications, including pneumonia, acute respiratory distress syndrome (ARDS), and multiple organ failure. H3N2, conversely, can cause serious complications, but they are generally less severe than COVID-19.

Could H3N2 cause the next pandemic?

According to media reports, the ability of a virus to cause a pandemic is determined by a variety of factors, including its ability to spread easily from person to person, its severity, and the availability of effective treatments and vaccines. The H3N2 strain is not as contagious as COVID-19, but like previous flu pandemics, it can spread quickly and cause severe illness and death.

Preventive Measures To Be Taken

Here is the list of some H3N2 virus prevention measures:

  • Maintaining good hygiene is very important to prevent infections spread through respiratory droplets.
  • Avoid crowded places and wear a mask in public places.
  • Wash your hands with soap and water, especially after arriving at your destination, for example by public transport.

To prevent the severity of the infection, it is necessary to consult a doctor within the first 48 hours from the onset of symptoms. Do not self-medicate and do not use paracetamol and steam inhalation without consulting your doctor. Follow up on everything your doctor prescribes.

Final Words,

H3N2 influenza is a serious viral infection that can cause significant morbidity and mortality, particularly in vulnerable populations such as the elderly and children. Although there is vaccine for H3N2, the best way to prevent the flu and its complications is to take precautions such as washing your hands frequently and avoiding contact with infected people.

You can be tested to see if you are infected with the H3N2 virus. Apollo Diagnostics uses multiplex real-time PCR to detect five strains of influenza, including influenza A, influenza B, H1N1, and H3N2. Only one sample collection is required, and results are available within 12 hours. Book your exam now!


How does the H3N2 virus spread?

H3N2 flu spreads quickly from an infected person. Infected droplets can spread from person to person through air, direct contact, or surfaces.

Is H3N2 treatable?

Uncomplicated cases of H3N2 are treated like any other seasonal flu:

  • Get plenty of rest.
  • Drink fluids (juice, soup, water) to keep yourself hydrated.
  • Over-the-counter medications are used to relieve fever, headaches, and body aches.

What are the effects of the H3N2 virus?

Experts say the H3N2 influenza virus can cause severe kidney damage, especially in older adults and people with chronic medical conditions such as diabetes, high blood pressure, heart problems, or kidney disease.

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