After a sharp decline in 2020 and 2021, influenza and respiratory syncytial virus (RSV), a seasonal virus that usually causes mild cold-like symptoms, are coming back with a vengeance. The infection is surging and hospitalisation rate linked to it is the highest since 2010 in the United States. Noting the symptoms, immunologist Scott Hensley said, “It is possible that this year will be sort of the granddaddy of them all in terms of flu."
US CDC also issued an alert regarding the same.
But, the question is why there is a sudden surge in influenza and RSV this year.
Why there is a sudden increase in influenza and RSV symptoms?
Not suitable environment for RSV to spread: For the last two years, factors such as temperature and humidity suitable for RSV to spread were not favourable, an epidemiologist at the Yale School of Public Health in New Haven, Connecticut pointed out, as quoted by the scientific journal Nature.
And this factor has made the population, especially children, immunologically naive to the virus, said Hensley, who is currently with the University of Pennsylvania. Normally, children get infected by their second birthday. Now, “you’re going to end up having kids that are three, four years of age right now who have never seen RSV".
Waning immunity among the adult population: Among the older population, who have been exposed to the virus, the problem is waning immunity. Every year, the population gets exposed to a small bit of virus and that significantly increases the antibody level. But “that kind of asymptomatic boosting maybe hasn’t happened in the last few years," John Tregoning, an immunologist at Imperial College London, told Nature magazine.
Covid caused immune deficiencies: Some experts have also pointed out on social media that Covid infection might have caused immune deficiencies among people and that is why people are more susceptible to other infections now. However, there is no evidence to support this theory.
Omicron provided short-lived protection against flu: On the other hand, there is another theory that suggests infection with one virus can raise a strong innate immune response that might prevent infection with another virus.
Hensley points out that last year’s first wave of influenza declined soon after the Omicron surge began. Perhaps Omicron infection provided some short-lived protection against flu. Or maybe the Omicron surge simply convinced people to mask up and keep their distance.
This virus causing more hospitalisation than COVID? Experts explain why | Mint - Mint
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