What data and experts say about what to expect from the flu and coronavirus in the coming weeks

While the flu grabbed all the media and social attention this winter, the coronavirus continued to spread without causing much of a stir. The latest weekly SiVIRA report released by the Carlos III Health Institute confirms that the downward trend in primary care has consolidated and hospitalization rates have begun to decline. The question of how long it will take until the peak of the epidemic is reached has been answered, but that doesn’t mean the respiratory virus season is over.

The winter dance between respiratory viruses means that when one virus goes down, another goes up, exploiting the gap left by its partner, and is defeated by our immune systems — only temporarily. Now that influenza has confirmed its downward trend, the question becomes: What now?

Will there be a second flu peak?

The 2021-22 season has seen an anomaly in the spread of influenza, a result of changing viral dynamics during the pandemic: two peaks – influenza A, H1 and H3 – the second of which was in the summer, And the virus didn’t stop circulating at basal levels throughout the summer until its levels were rising again in September. There is a second peak of influenza B in the 2022-23 season, but this peak is more serious than the first peak of influenza A, which is also very unusual.

It’s impossible to predict the future, but there are several scenarios that could happen in the coming weeks. Inmaculada Casas, Director of the Research Group on Respiratory Viruses and Influenza at the Carlos III Institute of Health, explained to elDiario.es: “Respiratory viruses replace each other when the ecological niche allows.” Currently the H1 subtype of influenza A dominates, and after its decline What awaits us?

“We don’t know what will happen: The H1 virus may be replaced by the H3 subtype or influenza B within a week or two,” Casas said. So far, none of these viruses have spread. “A is always followed by B, except for an epidemic every four or five years, where it’s the other way around.” So there may be a “small rebound” of influenza B, “and at the end of the season, influenza B is always much lower.” , just like spring.”

Raúl Ortiz de Lejarazu, honorary director of the National Influenza Center in Valladolid, agreed that “no one can know” what will happen. He clarified: “If there were a second peak of the epidemic, as separated as the previous two seasons, it would be abnormal because nothing like this has ever happened before.” In this hypothetical case, “the results would be It’s been an unusually long flu season.”

Will there be a new epidemic peak of covid-19?

There are three things in life: death, taxes, and one variant of SARS-CoV-2 followed by another taking its place. The question is therefore not whether a new lineage will replace an existing one, but whether this change will lead to a peak in the prevalence of cases that can be noticed at a societal or even hospital level. If the flu doesn’t make a comeback this winter, the next suspect is always COVID-19.

So far, this has not been the case. The latest SiVIRA report states that “covid-19 incidence rates in primary care continue to fluctuate”, with the report’s assessment unchanged from other weeks. In terms of hospitalizations, “hospitalization rates are lower than in the previous two seasons,” Amparo Larrauri, head of the Influenza and Other Respiratory Viruses Surveillance Group of the National Center for Epidemiology, said in a statement to the Ministry of Health . Science Media Center. The reasons are not surprising: “a degree of natural immunity due to previous infection and the success of the national vaccination program since its inception,” the researchers added.

Between vaccines, infections, and reinfections, our bodies are immunologically coping well with coronaviruses, which haven’t stopped spreading over the years. “Everything that is circulating is omicron, the virus has not changed much, even though the spike has a lot of mutations, and the vaccine is still very effective,” Casas explained. He recalled that the dose adapted to the XBB.1.5 variant “was consistent with Compared to the original lineage, “they are well adapted to the latest evolution of the virus” and therefore “they are better suited to the current epidemiological situation.” ”

Still, Casas believes SARS-CoV-2 will continue to spread “as before” at levels that are “not negligible, but not like the flu,” and he doesn’t think it will lead to a large-scale outbreak unless the coronavirus “reinvents itself and A lot has changed.”

Casas clarified: “If influenza stops circulating, we will have spring viruses, such as metapneumoviruses, that will take over this niche because children now have almost no antibodies against them, whereas they do have antibodies against SARS-CoV- 2.” Now “there’s no tendency for another coronavirus outbreak like there was in the beginning because it’s a great constant, it’s always been there and it hasn’t stopped spreading.”

Has the flu broken records this year?

All the media attention this year has been focused on the flu, and not without reason. The public had not followed respiratory virus season so closely until 2020, and they wondered if this was normal. The summary and preliminary answer is that the situation is not particularly serious, but about the same.

“Comparing these influenza events with historical influenza series before the Covid-19 pandemic requires complex analysis and taking into account changes in surveillance systems before and after,” Larrauri warned last week. “With appropriate analytical adjustments, We found that influenza transmissibility reached high levels during the peak of activity in the season but was still within the upper limits of pre- and post-pandemic influenza prevalence.”

LaLaurie said this situation is “not uncommon” and we have seen it in previous seasons such as the 2014-15 season. Ortiz de Lejarazu also believes that this season is “not at all anomalous from an epidemic point of view, neither because of the timing, nor the people affected, nor its severity, nor its intensity .”

To this, we must add that although flu vaccine coverage among people over 65 years of age has not yet reached the expected level of 75%, it continues nationwide to reach the record percentages observed during the civid-19 pandemic. If that fell to 68.5% from 69.5% last year, then this season – according to preliminary figures from the Sanofi survey – it fell to 63.2%, but is still well above pre-pandemic numbers – down from 58% ——.

Even so, Ortiz de Lejarazu believes that this season has been “extraordinarily unusual” due to a number of factors, such as “the lack of emphasis on[the Ministry of Health]following the reduction in influenza activity during the pandemic.” Need to expand coverage (vaccines).” “”.

Can Covid-19 turn into a cold?

Debate about the long-term burden of the presence of new respiratory viruses is nothing new, but data from many countries in recent weeks have revealed a strange paradox: Although SARS-CoV-2 is circulating at high levels , but both hospitalizations and deaths hit record lows.

Case in point: In the U.S., the CDC had to clarify that although infection levels were 27% higher than the previous year, according to wastewater testing, emergency room visits, hospitalizations, and deaths were down — 21, 22 and 38%, respectively. Similarly, in the UK, hospitalization and ICU admission rates for covid-19 have never been lower, leading some researchers to wonder whether the JN.1 variant (which is essentially caused by the population’s immune wall) is less severe.

“This change in the relationship between infection levels and disease severity is associated with higher levels of immune protection provided by the vaccine, previous infection, or both,” the CDC explained in the analysis. If the gap continues to widen , SARS-CoV-2 has the potential to complete its journey and join the ranks of other human coronaviruses that infect us every year in the form of colds. How long it will take to reach your destination (if ever), only time will tell.

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