Flu cases on rise, experts blame mutated strain, dropping of masks

After two years of the pandemic, there had been sudden rise in flu cases that is being attributed to the phasing out of mask-wearing by people and a possible mutation in the influenza strain doing rounds, say experts.

The Indian Council of Medical Research (ICMR) has said that Influenza-A subtype H3N2 is the major cause of current respiratory illness. “ICMR-DHR conducted a pan-respiratory virus surveillance across 30 virus research and diagnostic laboratories,” ICMR said, while issuing a detailed advisory.

Noted virologist Jacob John said these viruses have always been around but the spread was muted the past two years due to masking. “The virus has now found fertile ground. There is an accumulation of people who did not get it,” John said.

While people of all age groups are getting infected, doctors are seeing an increased number of cases among children and the elderly.

“We are seeing a 200 per cent increase in flu cases since November 2022. However, after the second half of February 2023, there has been a decline,” said Rajiva Gupta, Consultant-Internal Medicine, CK Birla Hospital.

Doctors cite three major reasons behind this increase in cases: cold weather from November to January, environmental pollution and greater prevalence of viral infections.

“The flu cases started appearing in October-November and have not stopped since. It starts with a sore throat and many then develop bronchial problems. It seems like a combination of different viruses,” said Rommel Tickoo, director, internal medicine, Max Healthcare.

The current strain in circulation, H3N2, has its origin in the 1968 pandemic.

However, experts also said that campaigns created about viruses during the Covid outbreak have made people more aware of virology and specific strains. “These viruses have been around for very long and people have been getting infected. Now they know the name of their respiratory infection,” Jacob said.

That said, some doctors feel the strain itself has mutated and the current formulation of the vaccine is unable to tackle this flu. A senior industry source said the World Health Organisation (WHO) is expected to come up with a new formulation of the vaccine, taking into account the strain doing the rounds. “WHO picks up a few strains for the influenza vaccine. It was more effective two years ago than now. It is a common flu but it keeps mutating. We are expecting WHO to issue guidelines on the new strain,” the source said.

The other issue is a lack of awareness about the influenza vaccine, which has to be taken every year. “Even the educated lot don't know about this vaccination. You can still get the flu but it wouldn't be as severe. October-November, at the onset of winter, is a good time to get this vaccination,” Tickoo added.

Doctors also said that during the same time last year, the Omicron variant of coronavirus was more prevalent and common flu cases were fewer in number.