A brief on H3N2 Virus infection

Influenza A virus is responsible for the majority of flu cases in winter season. In the present season, the majority of cases in Delhi/ NCR region are due to a subtype of influenza A, known as H3N2. There is a need to know about this virus, amidst raising cases of flu. Let us understand more about this virus and disease.

What is H3N2 infection?

1. H3N2 is a variant of Influenza A virus that is responsible for causing flu like illness in humans. It is the causative agent for most flu cases in Delhi in winter of 2022-23.
2. Influenza, also known as flu, is a contagious respiratory disease that is caused by a family of viruses known as influenza viruses that infect nose, throat, upper respiratory tract and in certain cases, they are also known to infect lungs
3. These viruses may cause illness ranging from mild to severe.

What are the types of Influenza virus?

1. There are four types of influenza viruses - the influenza A, B, C, and D virus. These viruses usually cause seasonal epidemics of influenza every winter or so-called flu season
2. Influenza A viruses are further subdivided into various subtypes based on two proteins on the surfaces of virus - hemagglutinin and neuraminidase.
3. There are eighteen different types of hemagglutinin, H1 through H18 and 11 different subtypes of neuraminidase, N1 through N 11.
4. Currently the subtypes of influenza A that are in circulation are H1N1 and H3N2.

Which were the pandemics caused by the Influenza virus?

1. The H1N1 variant was responsible for pandemic known as swine flu in 2009 and has continued to circulate seasonally. Much earlier, influenza virus was also responsible for the deadly Spanish flu pandemic of 1918.
2. Since then, the virus has undergone various genetic changes and has mutated to H3N2.

How does H1N1 change to H3 N 2?

What are mutations?

1. These changes occur through mutations. Mutations are small changes in the genes of the virus. Some mutations make the virus more vulnerable and unstable while some others they change the properties of transmission etc for that virus.
2. Viruses mutate to adapt to their surroundings and more effectively move from one host to another these mutations can cause viruses to better evade an immune system treatment and vaccines.

What are the symptoms of H3N2 virus infections?

1. The majority of the present flu cases in Delhi are caused by H3N2 virus.
2. Symptoms of H3 N2 virus infections are
3. Cough
4. Runny or congested nose
5. Sore throat
6. Headache
7. Body aches and pains
8. Fever
9. Chills
10. Fatigue
11. Diarrhea
12. Vomiting

How is H3N2 virus infection detected?

1. Since H3 N2 virus infection symptoms are similar to the other flu symptoms, the mainstay of diagnosis remains laboratory testing
2. The sample for laboratory testing of H3N2 is similar to the sample collected for COVID-19 testing that is the nasal swab and pharyngeal swab.
3. The method of testing for H3N2 is also similar to COVID-19 testing, that is RT PCR test.
4. The report is generated within a few hours of sample collection.
5. If an individual is tested positive for H3N2, the physician usually administers medication in form of antiviral drugs and other flu medications

What are preventive measures against H3N2 virus infection?

1. If one is tested positive for H3N2 the preventive protocol to be followed is similar to COVID-19. One should practice proper hand hygiene, social distancing and isolation
2. Even though the H3N2 infection does not usually cause critical illnesses, care must be taken as it may cause serious disease in elderly and immunocompromised people.

Should I be worried about H3 N2 virus infection?

While there is no reason for being panicky however it is important to be cautious of the H3N2 infections. Proper preventive measures, timely testing as well as treatment can reduce the complications of infection