H1N1 influenza cases have been reported at a number of hospitals across Chennai in recent weeks.

Suresh Kumar, senior consultant, Infectious Diseases, Apollo Hospitals, said they have been seeing H1N1 cases over the past one-and-a-half months, with at least three to four patients presenting to the outpatient department every day and a few requiring hospital admission.

“H1N1 influenza has surfaced even before winter. We usually see cases in September and October but this time, they have surfaced a little earlier,” he said, adding that there have been more cases of influenza A virus.

“Some patients have had severe presentations, including severe body ache, head ache, back pain and extreme fatigue. These severe presentations have been seen across all age groups. In fact, nasal symptoms such as runny nose and sore throat have been minimal in some, while some have also reported loose stools,” Dr. Suresh Kumar said.

He noted that the recommended vaccine for this season is expected to hit the market by the end of the month. “It is important to get vaccinated against H1N1. A few patients have required intensive care, prone ventilation and oxygen support,” he added.

Madhumitha R., senior consultant, Infectious Diseases and Infection Control, MGM Healthcare, said that while H1N1 cases have appeared a little earlier this year, the infection is endemic and can be seen at different times of the year. There are short-term rises in cases often followed by a decline in numbers. For instance, there was a spike in cases during summer.

“But yes, we have been seeing quite a lot of H1N1 influenza cases, specifically influenza A, over the last few weeks. People are presenting with symptoms such as fever, cold, cough and sore throat,” Dr. Madhumitha said.

“Influenza vaccines are available throughout the year, with vaccine formulations updated periodically to match the circulating strains and the requirements of the Northern and Southern Hemisphere influenza seasons. Vaccination helps reduce the risk of severe influenza, and highly vulnerable groups, including older adults, pregnant women and people with underlying medical conditions, should be vaccinated yearly,” she said.

The rise in influenza cases has also been observed among children. Janani Sankar, medical director, Kanchi Kamakoti CHILDS Trust Hospital, said they are seeing more cases of influenza A over the last two weeks and recommend following standard preventive measures, including practising cough etiquette, maintaining hand hygiene and getting vaccination against influenza.

A government doctor said they are seeing mixed flu-like illness but are unable to confirm H1N1 influenza due to lack of testing. “Patients are presenting with symptoms of fever with headache. Some of them develop gastric symptoms and diarrhoea. Patients improve with symptomatic treatment and antibiotics. In a few patients, the sickness worsens and they require IV injections. Many of them develop leucopenia and thrombocytopenia but resolve in a few days,” he said.

Noting that respiratory symptoms are few this season, he added that they start patients on Oseltamivir if there are any moderate respiratory symptoms.

S. Chandrasekar, Professor and Head, Department of Medicine and Critical Care services, Government Stanley Medical College Hospital, said there had been cases of H1N1 influenza two to three weeks ago, but they were mild in nature. Patients presented with cough, fever, headache and body ache. The symptoms generally lasted three to five days before improving. However, some persons continued to experience exhaustion, while vulnerable groups, including the elderly, reported prolonged illness.

“We expect a surge in cases in the coming months due to the monsoon. Vaccination is the best way to prevent infection, and August and September are the right time to get vaccinated,” he said.

Published - August 15, 2026 09:34 pm IST