Delhi is recording a sharp rise in H1N1 influenza cases this monsoon, with 1,349 infections reported so far this year compared with 229 during the same period in 2025, marking a nearly six-fold increase.

Delhi Health Minister Pankaj Singh said regular testing is being carried out across the city and that patients diagnosed with the infection are receiving treatment.

Government hospitals have also made arrangements to handle the rise in cases, including dedicated wards and rooms for H1N1 patients.

Why are H1N1 cases rising in Delhi?

Hospitals have reported an increase in people arriving with cough, cold and high fever, particularly over the past few weeks. Dr Sanjeev Sinha, professor of medicine at AIIMS Delhi, told ANI that influenza cases tend to rise during the monsoon as temperatures change.

Dr Satish Koul of Fortis Memorial Research Institute, Gurugram, also told ANI that hospitals have been seeing around 7-10 H1N1 patients daily in outpatient departments.

The precise reason for this year's rise remains unclear, and further research is needed to determine whether viral changes or increased person-to-person transmission are contributing to the surge.

H1N1 symptoms to watch for

According to the World Health Organization (WHO), H1N1 continues to circulate each season alongside other influenza viruses, including H3N2. As a subtype of influenza A, it can cause symptoms similar to those of other respiratory infections. Common symptoms include:

• Fever
• Cough and sore throat
• Headache and muscle or body aches
• Runny nose
• Fatigue or weakness
• Chills

Nausea, vomiting and diarrhoea can also occur, particularly in some H1N1 infections. Most people recover from influenza within about a week, although the illness can become severe in some cases and lead to complications such as pneumonia.

H1N1 can affect people of all ages, but young children, older adults, pregnant women, people with diabetes or heart and lung conditions, and those with weakened immunity face a higher risk of severe illness. In some cases, the infection can progress rapidly and cause complications such as pneumonia or respiratory failure.

How to reduce the risk

Basic precautions can help limit the spread of H1N1. These include

• Getting the seasonal flu vaccine
• Washing hands regularly
• Covering coughs and sneezes
• Avoiding close contact when unwell
• Wearing a mask in crowded or poorly ventilated spaces