Flu season is around the corner, but cases of infection of respiratory viruses—influenza A(H1N1), A (H3) and influenza B—have already shot up throughout the country.

And what concerns doctors more are cases of the influenza B virus, whose lineage is undetermined and has been rising alarmingly, which indicates mutation in the virus variant.

“October-November is the peak flu season in Nepal, but multiple respiratory viruses have been spreading in our country,” said Dr Sher Bahadur Pun, chief of the Clinical Research Unit at Sukraraj Tropical and Infectious Disease Hospital. “As very few people in Nepal get flu shots, elderly people and those having compromised immunity will be at risk of getting severe from infection of the respiratory viruses.”

According to the World Health Organisation’s Global Influenza Surveillance, over 386 influenza cases have been reported in Nepal since the start of 2023. Of the total, 225 cases are A (H3), also known as Hong Kong flu, 29 are A(H1N1), also known as swine flu, 48 are influenza B of Victoria lineage, and 84 are influenza B lineage undetermined.

Such cases of infections could be far more than what is recorded, as all cases do not reach hospitals and undergo testing.

“We can expect more cases of respiratory infection in the coming days, as influenza virus becomes more active during seasonal transitions,” said Dr Rajiv Shrestha, an infectious disease expert at the Dhulikhel Hospital. “Those who can afford it should take an influenza vaccine. It will be better if people above 50 years of age and those having compromised immunity get inoculated with flu shots.”

The seasonal influenza virus causes respiratory complications, which affect the lungs. It spreads quickly in communities. The diseases can cause fever, cough, body aches, occasional vomiting, diarrhoea and pneumonia.

Experts say early diagnosis is crucial to prevent infection. Patients recover early if treated on time. Experts also said that both the severity of the disease and deaths increase if seasonal influenza cases are not diagnosed in time.

Public health measures—mask-wearing, handwashing, avoiding crowds, and maintaining social distancing—can reduce infection, according to doctors.