H1N1 Dominates Influenza A Cases Across India

Why in the News ?

The Indian Council of Medical Research (ICMR) has reported that H1N1 constitutes nearly 98% of Influenza A infections currently detected in India. The ICMR has also clarified that the circulating strain is the familiar H1N1 pdm09 seasonal virus.

Current Influenza Situation in India:

●     According to ICMR Director-General Rajiv Bahl, nearly 98% of Influenza A cases currently identified in India are caused by H1N1.

●     H3N2 accounts for only around 2–3% of the detected Influenza A infections.

●     The increasing detection of H1N1 in several States has generated public concern about a possible resurgence of severe influenza.

●     However, the ICMR has advised the public not to panic, as the circulating virus is not a newly emerging strain.

●     The predominant virus is H1N1 pdm09, which first became prominent during the 2009 influenza pandemic.

●     Since then, H1N1 pdm09 has evolved into a seasonal influenza strain and continues to circulate periodically.

●     The current situation therefore reflects the circulation of an already known seasonal influenza virus rather than the emergence of an entirely new pandemic strain.

Vaccination & Public Health Advice

●     The ICMR has stated that there is no immediate need for the general population to take seasonal influenza vaccination solely because of the present H1N1 prevalence.

●     Vaccination decisions should instead consider age, underlying health conditions and individual risk factors.

●     People aged above 65 years may discuss seasonal flu vaccination with their doctors.

●     Immunocompromised individuals are also advised to seek medical guidance regarding vaccination.

●     Such a targeted approach can help prioritise vaccination for groups that may face a higher risk of complications.

●     Public health authorities continue to rely on influenza surveillance to track changes in circulating strains and detect unusual patterns.

 About Influenza Viruses:

●     Influenza is an infectious respiratory disease caused mainly by Influenza A and Influenza B viruses.

●     Influenza A viruses are classified according to two major surface proteins: Haemagglutinin (H) and Neuraminidase (N).

●     H1N1 and H3N2 are important subtypes of Influenza A.

●     Antigenic drift involves gradual genetic changes that enable influenza viruses to evade existing immunity and contribute to seasonal outbreaks.

●     Antigenic shift is a major genetic change, mainly associated with Influenza A, which can potentially create a novel virus with pandemic potential.

●     Influenza surveillance is important for early detection, vaccine composition, outbreak preparedness and pandemic risk assessment.

●     The issue is relevant to UPSC through public health, epidemiological surveillance, vaccination policy, zoonotic diseases and pandemic preparedness