Are Influenza A H1N1 & H3N2 similar?

Have you noticed how everyone around us seems to be falling sick these days? They are suffering from a fever, a cold, body aches, and headaches. One might think that it is the COVID-19 infection, given how we have just survived a global pandemic. But turns out, it is just the flu caused by some strains of the Influenza A virus.?

Back in 2009, there was a viral outbreak that caused a pandemic worldwide with a high mortality rate. It was called the Swine Flu and was caused by the H1N1 strain of the type A Influenza virus. It was controlled before it could lead to COVID-19-like severity, which was caused by SARS-CoV-2 and has a much higher mortality rate.?

Nonetheless, it was a pandemic that led to thousands of deaths. Swine flu has now become the seasonal flu, over a decade after its breakout.?

What is Influenza A Virus?

Influenza A refers to a group of viruses that can cause respiratory problems upon infection. While influenza A viruses are mostly seen in birds and animals, they can also infect humans directly upon contact with an infected species, leading to flu.?

There are multiple subtypes and strains that might result in minor to severe health complications. Hemagglutinin (H) and neuraminidase (N), two surface proteins that evolve over time to create new viral strains, serve as a classification system for Influenza type-A viruses.

Influenza A H1N1 and Influenza A H3N2 have both caused major health problems, especially in humans. While the 2009 Influenza A H1N1 pandemic was the first to affect humans, the Influenza A H3N2 virus has been around for many years and occasionally causes seasonal outbreaks.

How Similar Are They?

Both the H1N1 and H3N2 strains belong to the same group of viruses, so there are a lot of similarities that can be found between them. Let us discuss where they are similar and yet different from each other.

Transmission

Both H1N1 and H3N2 subtypes spread through airborne transmission of respiratory droplets. These droplets containing the virus are released into the air when a person with the infection coughs or sneezes. So when a healthy person inhales the same air, they get infected with the virus as well. And since the virus can briefly live on outside surfaces, getting infected by touching a contaminated surface and then touching your face is also possible.

Symptoms

Common flu symptoms, such as fever, coughing, sore throat, body pains, and fatigue, are caused by both the H1N1 and H3N2 subtype infections. But children are more prone to nausea, vomiting, and diarrhea as well.

Although the severity of the symptoms can differ, some people may only have mild symptoms, while others may experience serious complications like pneumonia, respiratory failure, and perhaps even death. Children, the elderly, pregnant women, and those with other underlying medical issues are at a higher risk for developing severe symptoms.

Genetic Makeup

The genetic makeup of the H1N1 and H3N2 subtypes differs, and unique hemagglutinin and neuraminidase protein combinations are present. The virus can attach to and enter human cells thanks to hemagglutinin on its surface. Neuraminidase, on the other hand, helps the virus leave infected human cells and enter new host cells.

Interestingly, the H1N1 subtype contains a hemagglutinin protein derived from a swine influenza virus and a neuraminidase protein derived from a human influenza virus. Whereas the H3N2 subtype contains a hemagglutinin protein derived from a bird influenza virus and a neuraminidase protein derived from a human influenza virus.?

These genetic differences can affect the way the virus interacts with human cells, the severity of the symptoms it causes, and the vaccines that are effective against it.

Vaccination

H1N1 and H3N2 require separate vaccines because their hemagglutinin proteins are different. The World Health Organization (WHO) makes recommendations each year regarding which influenza virus strains should be included in the seasonal flu vaccine.

Depending on the likelihood and expected circulating strains for the coming flu season, the vaccine comprises a combination of three or four influenza virus subtypes, including H1N1 and H3N2. The flu vaccination is the most effective strategy to prevent infections and lessen the severity of disease, and it is updated each year to match the circulating strains.

Further precautions can help in preventing the spread of H1N1 and H3N2. They include keeping your hands clean, covering your mouth and nose when you cough or sneeze, avoiding direct contact with sick individuals, and staying in when you are unwell.

Those who are at high risk of medical comorbidities should take extra precautions, such as avoiding crowded areas and seeing a doctor right away if they have flu-like symptoms.

Let us take a look at some of our case studies and doctor talks.?

Health Talk: Know More About H3N2 Virus | Yashoda Hospitals Hyderabad

Health Talk: Flu Outbreak in India and Its Management | Yashoda Hospitals Hyderabad

Health Talk on Seasonal Viral Fevers by Dr. Arshad Punjani | Yashoda Hospitals Hyderabad

Webinar: Severe Influenza Overlap in BA 5 Covid Surge | Yashoda Hospitals Hyderabad

Are You Suffering From Any of the Flu Symptoms?

Appropriate treatment is necessary, as it ensures that your life goes on as normally as possible. And given the potentially life-changing consequences of treatment and surgery, it is always critical to seek a second opinion from a medical professional.?

Get a free expert second opinion from Yashoda Hospitals.?

Share your thoughts in the comments section below and let us know what you'd like to see in our next week's newsletter.?

If you liked it, please share this edition with your friends and family.