H1N1 cases are rising in Delhi-NCR, and doctors are reporting patients with influenza-like illness as well as some developing breathing complications.

But while the increase has put respiratory symptoms under the spotlight, doctors stress that not every cough or episode of breathlessness during the current flu season means severe H1N1. Delhi has reported 1,449 H1N1 cases up to August 12, 2026, more than six times the 229 cases reported during the same period last year, according to National Centre for Disease Control (NCDC) data.

Hospitals including Ram Manohar Lohia Hospital and Safdarjung Hospital have strengthened arrangements to manage influenza and possible complications. 

"Not every H1N1 infected patient gets breathing complications and most of them get cured with support care,"says Dr Chirag Tandon, Director - Internal Medicine, ShardaCare - HealthCity. However, he says patients whose lower respiratory tract is affected can develop breathing problems and complications such as pneumonia.

Dr Manoj Kumar Goel, Principal Director & Unit Head - Pulmonology & Sleep Medicine, Fortis Memorial Research Institute, Gurgaon, similarly warns that severe infection can put the lungs under significant stress.

So, when does breathlessness during H1N1 become a serious warning sign?

Why Are Some H1N1 Patients Developing Breathing Problems?

H1N1 is an influenza A virus that primarily affects the respiratory tract. Most infections remain uncomplicated, with symptoms such as fever, cough, sore throat, headache, muscle aches and fatigue. WHO says most people with non-severe influenza recover without requiring medical attention.

But influenza can sometimes progress to lower respiratory tract infection and pneumonia. Dr Tandon explains that the virus can damage the airways and lung lining, with inflammation interfering with the lungs' ability to transfer oxygen into the bloodstream.

"A serious case of this could cause pneumonia thereby impeding gas exchange, an adequate transmission of oxygen to the bloodstream from the lungs," he says.

Dr Goel adds that the concern is not simply the presence of a cough or fever, but whether the infection is beginning to impair lung function. WHO identifies shortness of breath, fast breathing, hypoxia and pneumonia as indicators of severe or complicated influenza.

Patients can also develop acute respiratory distress syndrome (ARDS), sepsis or respiratory failure.

Source: ndtv