Flu virus strain in circulation causing more severe symptoms: Dr Gagandeep Kang

Top virologist Dr Gagandeep Kang is associated as a professor in the department of gastrointestinal sciences with the Christian Medical College (CMC) in Vellore, Tamil Nadu.  She has been a prominent scientific voice, simplifying the complex details around viral infections since the time COVID-19 took the world and India by storm.

In this chat with Moneycontrol, she explains why many cities in India are in the grip of a seasonal flu outbreak and the worries around the spread of avian influenza.

Edited excerpts:

Many cities in India are seeing a major surge in flu cases, with most people reporting more severe symptoms that are also long-lasting. What do you think are the reasons? Do we know enough? Does COVID-19 have any role to play, directly or indirectly?

There is a variation in severity among influenza strains, in addition to the variation in clinical presentations that come -- variations by age and previous exposure or vaccination.

For example, in 2009, H1N1 was relatively mild with a high rate of asymptomatic infections, but in other outbreaks, it has been more severe. This particular H3N2 strain (of the Influenza A virus) seems to be causing more bronchitis as well as associated symptoms such as diarrhoea and conjunctivitis, which are somewhat less common, usually, with influenza.

This has nothing to do directly with SARS-CoV2. Indirectly, we could say that it might have something to do with COVID-19 because there was less intermingling of people for a couple of years, so there was less circulation of respiratory viruses than usual.

Once people start interacting again, influenza viruses have the opportunity to transmit at high rates again.

Also read: A lingering cough, occasional fever: All about the H3N2 flu sweeping across India

Is there something that can be done to mitigate the situation or do you think the influenza virus will run its course?

Influenza vaccines are available and we should be using them. I don't think healthy young people need annual vaccines, but the elderly should certainly take them. They are not the greatest vaccines, but in most seasons, they work. For the generally healthy, your bodies will handle the infection. Uncomplicated influenza needs only supportive therapy, such as cough medicine. Severe or complicated influenza, on the other hand, may benefit from neuraminidase inhibitors like Oseltamivir and adjunct therapy, including steroids.

Do you see a need to strengthen influenza and COVID-19 surveillance to assess viral infections in a better way?

Absolutely. The Indian Council of Medical Research (ICMR) has a network that is doing excellent respiratory virus surveillance and is planning to expand age groups where surveillance is done. Sustained surveillance of severe acute respiratory illness and milder influenza-like illness should be in place in all countries, as it is in India.

Perhaps some expansion for local data may be valuable in India, but we have a good sense of what is happening—this was not the case a few years ago.

The spread of the H5N1 variant of bird flu virus has triggered concerns in many parts of the world and recently its spillover to humans resulted in a girl’s death in Cambodia. Some scientists are saying that this virus now seems more adaptable for transmission into humans. Can bird flu virus emerge as a major threat globally in the near future?

Yes, this is a significant concern. Influenza A/H5 (H5N1) viruses have caused infrequent spillovers into humans since their emergence in 1997. There have been 870 reported human cases of A/H5 infection globally, which have resulted in over 450 deaths. This points to the high fatality rates. The ability of influenza viruses to cross species is the reason why public health authorities are so concerned about avian influenza.

While avian influenza is a serious illness and any zoonotic transmission is concerning, it is, as can be seen from the numbers, still rare in humans, and is typically linked to direct contact with infected birds or their droppings. No H5N1 avian influenza virus has been demonstrated to have had sustained human-to-human transmission.

Last month, the Ministry of Health, Cambodia, confirmed human influenza due to H5N1 and the patient died. Full genome virus sequence was available on GISAID (a global repository that provides open access to genomic data of influenza and SARS CoV viruses) three days back. The H5N1 virus, isolated from the cases in Cambodia, shows changes that were anticipated and have been found in previous avian and human strains when they go from a bird to a human. This does not indicate that the virus has mutated to become human-to-human transmissible. Therefore, waiting and watching very carefully is the appropriate strategy.

Also read: Influenza outbreak in several cities; patients report severe, longer sickness

Do you think India is better equipped to detect and respond quickly and adequately to future outbreaks of viral infections post COVID-19? If not, what may still be missing?

Yes, we are definitely better off now than we were before. We can and should maintain our surveillance structures, and also think about what we need to do beyond respiratory virus surveillance, to include other syndromes such as fevers, diarrhoea, hepatitis, etc.