Cases of H1N1 influenza have been reported in a number of hospitals across Chennai in recent weeks.
Suresh Kumar, senior consultant infectious diseases at Apollo Hospitals, said they have been witnessing cases of H1N1 infection over the past one-and-a-half months, with at least three to four patients coming to the OPD every day and a few of them requiring hospitalization.
“H1N1 influenza has appeared even before winter. We usually see cases in September and October, but this time it appeared a little earlier,” he said, adding that there are more cases of influenza A virus.
“Some patients had severe symptoms, including severe body aches, head pain, back pain, and extreme fatigue. These severe symptoms were seen in all age groups. In fact, nasal symptoms such as runny nose and sore throat were minimal for some, while others also reported loose stools.”
He pointed out that the vaccine recommended for this season is expected to reach the market by the end of this month. He added: “It is important to be vaccinated against the H1N1 virus. A small number of patients require intensive care, ventilation and oxygen support.”
Although H1N1 cases emerged early this year, the infection is endemic and can be seen at different times of the year, said Madhumitha R., senior consultant in infectious diseases and infection control at MGM Healthcare. There are short-term spikes in cases often followed by a decline in numbers. For example, there was a spike in cases over the summer.
“But yes, we have been seeing a very high number of cases of H1N1 influenza, specifically influenza A, over the past few weeks. People are showing symptoms like fever, cold, cough and sore throat,” Dr. Madhumitha said.
“Influenza vaccines are available year-round, with vaccine formulations updated periodically to match circulating strains and the demands of the Northern and Southern Hemisphere influenza seasons. Vaccination helps reduce the risk of severe influenza, and the most at-risk groups, including the elderly, pregnant women and people with underlying medical conditions, should be vaccinated annually,” she said.
An increase in influenza cases among children has also been observed. Janani Sankar, medical director of Kanchi Kamakoti Children’s Trust Hospital, said they have been seeing more influenza A cases over the past two weeks and recommend standard preventative measures, including practicing cough etiquette, maintaining hand hygiene and getting vaccinated against influenza.
A government doctor said they are seeing a mixed flu-like illness but are unable to confirm H1N1 influenza due to a lack of testing. He added: “Patients suffer from symptoms of fever and headache. Some suffer from stomach symptoms and diarrhea. Patients improve with symptomatic treatment and antibiotics. In a small number of patients, the disease worsens and they require intravenous injections. Many of them develop leukopenia and thrombocytopenia but recover within a few days.”
He pointed out that respiratory symptoms are few this season, and added that they start patients on oseltamivir if there are any moderate respiratory symptoms.
S said. Chandrasekar, professor and head of the department of medicine and critical care services at Stanley Government Medical College Hospital, said there had been cases of H1N1 influenza two to three weeks ago, but they were mild in nature. Patients suffer from cough, fever, headache and body aches. Symptoms generally lasted three to five days before improving. However, some people continued to experience fatigue, while vulnerable groups, including the elderly, reported long-term illness.
He added: “We expect an increase 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.”
Published – 15 August 2026 at 09:34 PM IST
