Over the past few weeks, Delhi-NCR has seen a sharp increase in viral illnesses. According to a LocalCircles survey of over 11,000 households, 69% reported at least one member displaying symptoms such as fever, cough, sore throat and respiratory distress.

Compared to earlier in the year (e.g. March 2025, when around 54% of households reported similar symptoms), the current outbreak represents a significant escalation.

Doctors and virologists point to influenza A's H3N2 subtype as the leading driver of this surge. What's unusual this season, however, is how many cases are more severe than typical seasonal flu, i.e. fevers lasting longer, over-the-counter drugs being less effective, and more hospitalisations, especially among vulnerable groups.

Given Delhi's dense population, high co-morbid disease burden (diabetes, respiratory illness, cardiac conditions), and extended monsoon conditions aiding viral spread, the situation is a public health concern. Prompt awareness, correct diagnosis, prevention and care can make a big difference before it worsens.

H3N2 is a subtype of Influenza A virus. Influenza viruses are categorised by surface proteins (haemagglutinin "H" and neuraminidase "N"). So, H3N2 refers to the type-3 H and type-2 N. It is one of the strains that causes seasonal flu, meaning it circulates in humans, mutates over time, and each season may have differing severity. 

Source:Ndtv