The rate of flu infections was almost non-existent due to the worldwide SARS-CoV-2 infections.
The influenza virus has been perplexing scientists since the 1800s. These viruses are responsible for causing widespread outbreaks with the most prominent and deadly pandemic being that of the 1918 Spanish flu pandemic caused by Influenza A strain. Influenza viruses undergo mutations by changing their surface conformation (via antigenic drift) quite rapidly thereby making it challenging to make a vaccine that can tackle all the strains. The influenza virus claims up to 6,50,000 lives per year globally. However, there was a dip in the number of flu infections in 2020, thanks to the SARS-CoV-2 pandemic.
According to the National Centre for Disease Control (NCDC), in 2020, India had approximately 2700 people suffering from the flu with around 40 deaths as compared to the previous year (2019) where almost 29,000 people had the flu and around 1200 people succumbing to the infection. There was a concomitant 14 per cent drop in the sales of cold and flu medicines especially the ones containing a combination of chlorpheniramine, paracetamol and phenylephrine. These subsiding statistics baffled the scientific community more than the influenza virus itself.
The COVID-19 pandemic made us re-evaluate our hygienic habits and exposed some of the public health concerns. Researchers speculate that the extra awareness of hygiene through washing hands, social distancing and wearing masks are the possible contributing factors to reducing the intensity of the flu occurrences. Due to the closing of the international barriers, the lack of movement between countries may have helped in curtailing the excessive influenza infections as the virus can migrate from one region to another through travellers and tourists.
School Going children are extremely vulnerable to the flu as they are in close contact with each other. The schools shut down during the pandemic, which helped in reducing the spread of droplet-based infections. Another reason why these statistics could be low is that many of the infected people were too afraid to go to the hospitals and get it checked, suspecting it to be a SARS-CoV-2 infection. The people who were previously administered the flu vaccines may have had improved immunity against the flu. These vaccines were also hypothesized to be protective against COVID-19 infections. The rate of flu infections was low even in countries that did not manage the pandemic efficiently.
The precautionary strategies employed to tackle the COVID-19 pandemic appears to have worked against influenza virus infections and other acute respiratory infections. Hundreds of viruses capable of causing symptoms similar to the common cold were also kept at bay, such as parainfluenza, metapneumovirus and respiratory syncytial virus (RSV). However, rhinitis or hay fever still prevailed due to rhinoviruses being stable on surfaces like desks and doorknobs for extended periods of time. Studies were conducted stating that a previous coronavirus infection (like the SARS or MERS of the early 2000s outbreaks) or a rhinovirus infection, extends immunity against the COVID-19 infection. This could be due to increased interferon production in the body (antiviral agents) brought on by the previous infections.
The lower number of flu infections is a good sign and has helped alleviate pressure off of the healthcare system. There is a matter of concern, nevertheless. Many scientists theorize that the virus could be evolving and mutating this year by laying low. The problem is that the immunological memory against the flu infection is very short-lived (around a year). Since many people are not getting the flu infection this year, it could be possible for the influenza virus to cause a more rigorous infection post the easing of the pandemic restrictions. The kids may also not be able to gain proper immunity by not being exposed to the influenza virus at a young age making them even more susceptible to a more robust form of the flu.
Some of the precautionary measures from the COVID-19 pandemic can be utilised for future flu infections. If a person has the flu, he/she can be granted a leave of four days (incubation time of the influenza virus) and wear a mask during the recovery period. With the working of viruses still being a mystery, most researchers suggest that people should be ready for the worst-case scenario as there is a prevailing fear of the resurgence of other infectious diseases post the pandemic.