Is flu season coming again?

We’re on the doorstep of fall, and experts still don’t know how the season will pan out. respiratory infection season – Respiratory syncytial virus (RSV), influenza, colds… – from 2023/2024.

According to comments 65 And more, We have no way of knowing whether there will be an epidemic more similar to what we knew before the health crisis caused by the coronavirus, or whether anomalies similar or different from those experienced last year will be repeated. Started earlier than expected There are two distinct peaks – the first is the November/December peak for influenza A and RSV, and the second is the January/February peak for influenza B.

Of course, what is currently known is that influenza and respiratory syncytial virus are currently at their lowest levels of transmission, and the most circulating pathogens are SARS-CoV-2, According to the latest data collected by the Acute Respiratory Infection Surveillance System.

Source: Acute Respiratory Infection Surveillance System.

“Influenza virus activity There are not always similarities between seasons. It seems appropriate to maintain a community surveillance system to monitor activity,” he said. José María Eros, Director of the National Influenza Center in Valladolid (@CentroGripe), is an organization recognized by the World Health Organization.

Furthermore, experts recalled the importance of studying in detail “information provided by experts”. Center for Southern Hemisphere Countries”, Where winter is coming to an end. “This is for us a very useful tool We regularly follow their notifications on virus activity, distribution and its virological and epidemiological characteristics,” he said.

Honorary Director, National Influenza Center, Raul Ortiz de Leharazu (@DrLejarazu), shared Eiros’ views on the unpredictability of the epidemic.

“Seasonal (winter) influenza infects 1 in 10 adults and 3 in 10 children, i.e., it does not infect the entire population every year. Antibodies generated by natural infection and vaccines develop over time (6 by 10 months), so there was a year without influenza (2020), another wave of less intensity and longer duration, with two very separate waves of the H3 subtype (2021), which emerged last year Very early cases and two clear waves, the first was influenza A and the second was influenza B, They don’t expect to have a completely normal season. When the stone of a pandemic is thrown into the lake of respiratory viruses, it leaves a wave that will take time to dissipate,” he reflected.

Source: Acute Respiratory Infection Surveillance System.

Epidemiologist and researcher at the Foundation for the Promotion of Community Health and Biomedical Research in Valencia (@GVAfisabio), Salvador Perot, He also doesn’t know much about the upcoming season.

“In the Southern Hemisphere, influenza occurs between April and September, while in the Northern Hemisphere, influenza occurs between October and May. Flu activity there provides clues to what might be happening here, but the same thing doesn’t necessarily happen here. will happen as the virus spreads in different areas they can be different in the world And the immunity of each population. As far as we know, some countries (Argentina, Australia…) experience “normal” seasons, while others (Chile, South Africa…) have a somewhat early season,” he noted. Specifically, “Strain A He noted that “although there are more cases of B in the South than in the North (more or less half the cases),” it is spreading there.

He agreed with Perot, Marta Lopez de Diegofrom National Center for Biotechnology-CSIC (@China Shipbuilding Industry Corporation), he pointed out that “infectious diseases caused by influenza viruses are unpredictable from an epidemiological perspective, especially in the wake of the Covid-19 pandemic, so it is difficult to know in advance whether there will be a rebound.”

Furthermore, he noted, “The epidemic has had a large impact on influenza activity.” “During February to March 2020, activity was high in most countries in the Northern Hemisphere, consistent with the typical season. However, from late March 2020 Global activity remained stable towards the end of 2021. The decrease was largely due to social reasons. Subsequently, from February 2022, with the easing of the above-mentioned policies, Influenza activity begins to return

to previous levels. It is true that last year the season with the highest incidence of influenza virus was earlier than in other years, but this may be because the loss of protection against this virus is so severe at the population level because of the low incidence of influenza viruses. Now, this season, activity is expected to return to levels similar to those seen in the years before the Covid-19 pandemic,” he predicted, assuring that there might also not be two flu peaks so separated.

Source: World Health Organization and Acute Respiratory Infection Surveillance System reports.

In the case of the immunologist and professor at the University of Valencia, Rafael Toledo (@alfwarrior), also believes that although prediction is not easy, “The next flu season won’t be as abnormal as the last flu season.”

“It will look more classic, Starting before 2020,” he commented. “I think the situation last year was fundamentally different because of the lower spread of the virus in previous years. This causes people to lose a level of immunity and become somewhat more susceptible,” he said.

Therefore, while it is still unclear which strains will prevail this season, it must be considered that “the return of some immunity at the population level” is likely to play a decisive role. What we lost” During the epidemic.

Comparison of several influenza seasons from 2010 to 2016. Source: National Center for Epidemiology, Carlos III Health Institute.

“The situation in Europe can be extrapolated from the situation in the Southern Hemisphere, which is now experiencing winter. Cases started to increase sharply in early May, with the onset season earlier than in previous years. Furthermore, numbers are above the five-year average (including the pandemic) but below This time in 2019 and 2022. The important thing to note is, infections in children, Possibly originating from non-immune and viral transmission during the first year of the pandemic,” noted the head of immunology services at CU Virgen de Arrixaca Hospital, Manuel Muro

(@manuelmuro5).

However, he reassured, “Flu it doesn’t have to be different – before 2020 – unless some strain emerges that is more virulent than other years. ”

Vaccination

Of course, while it is difficult to predict what will happen this fall, whether the epidemic will emerge like last year, or what will happen with other viruses such as respiratory syncytial virus, steps can be taken at the individual level to protect themselves and, in many cases, be the most effective. useful tools Still a vaccine.

Specifically, recalls the Director of the National Influenza Center in Valladolid, “some influenza vaccines can enhance the immune response against influenza viruses. Adjuvanted vaccines and high-load vaccines represent some great options For those who have to comply with the movement due to age criteria”.

And, he believes, fidelity to the vaccination campaign – which is high in Spain – “Ensure atypical reactions – More Complete – This represents a positive fact for vaccinated people and their environment.

“The effort to maintain good coverage is multifactorial; it must involve, From social agents to patient groups and health administrations”, The conclusion is.