Sometime in the spring of 2020, after centuries, perhaps thousands of years, of tumultuous cohabitation with humans, the flu suddenly darkened. around the world, Documented Viral infections completely destroyed Where the world tried to counter SARS-CoV-2. At this time last year, US experts The concern began that the unprecedented flu vacation was too strange to last: The cluster of viruses that cause illness may be preparing for an epic comeback, slamming us with “a little more punch” than usual, Richard Webby, an influenza expert at St. Jude Children’s Research Hospital, in Tennessee, told me at the time.
But those fears did not materialize. The 2021 winter flu season is back in the southern hemisphere again Frighteningly silent; in the north, Cases crept in December– Only to fade before the fade reappears in spring.
Now, with the weather once again cooling in this hemisphere and the winter holidays looming, experts are looking to the future with apprehension. after, after Skip two seasons In the Southern Hemisphere, the flu spent 2022 jumping across the lower hemisphere with greater enthusiasm than it has since the start of the coronavirus crisis. And among the three years of the pandemic that has spread so far, this one presents the strongest signs yet of a severe flu season to come.
It is still very likely that the flu will subside to mild for the third year in a row, making the most bleakest of experts’ doubts welcomely wrong. Then again, this year, virally speaking, is not like last year. Australia recently concluded an unusually early and “very important” season with influenza viruses, says Kanta Subbarao, director of the WHO Collaborating Center for Reference and Research on Influenza at the Doherty Institute. By the number of confirmed cases, this season has been one of The worst country in many years. in South Africa, “It was a very typical flu season” by pre-pandemic standards, which is still enough to be of interest, according to Sheryl Cohen, co-chair of the country’s Center for Respiratory Diseases and Meningitis at the National Institute of Infectious Diseases. Subbarao told me that after a long, long hiatus, the flu in the Southern Hemisphere “definitely returned.”
This does not bode terribly well for those of us in the North. The same viruses that sprout their seeds in the South tend to be the ones that germinate epidemics here as seasons turn their yearly vagaries. “I take the South as an indicator,” says Sima Lakdawala, an influenza transmission expert at Emory University. And if the flu returns here, too, with a vengeance, it will clash with residents who have not seen likes in years, and are already trying to organize reactions to many of dangerous pathogens simultaneously.
The worst-case scenario will not necessarily end. What happens below the equator is never a perfect indicator of what will happen above it: Even in times of peace, “We’re pretty bad at predicting what flu season will look like,” Webby, of St. Jude, told me. The coronavirus, and the world’s responses to it, has put experts’ few forecasting tools in even greater trouble. But the experiences of the South can be telling. In South Africa and Australia, for example, many COVID mitigation measures, such as recommendations for global disguise and post-travel quarantine, have been lifted with the onset of winter, allowing respiratory viruses to flow through the population. The flu flood also started two years after essentially flu-free – which is good on the face of it, but also represents several months of missed opportunities to update people’s defenses against the flu, leaving them more vulnerable early in the season.
Some of the same factors are working against those of us north of the equator, perhaps to a greater degree. Here, too, the population is starting from a lower baseline defense against influenza — especially young children, many of whom have never struggled with viruses. Webby said it was “very, very likely” that children would end up being disproportionately beaten Looks like he was in Australia– Although Subbarao points out that this trend may be driven by more cautious behaviors among the older population, which skews the disease to a younger age.
Pay attention to vaccinations, too decreased during the epidemic: After more than a year of calls for booster after booster, “people are experiencing a lot of fatigue,” says Helen Chu, MD, a flu expert at the University of Washington, and that fatigue could actually drive interest in flu vaccines down even further. (During the good years, influenza vaccine prevalence in the United States peaked About 50 percent.) And the little virus protection that was still in place last winter is now completely gone. In particular, schools – a component of flu transmission – have significantly relaxed since last year. Webby said there is also “more flu around the world” all over the global map. With international travel back in full swing, viruses will have many opportunities to move across borders and ignite outbreaks. And should such a pandemic emerge, with health infrastructure already under strain from the simultaneous outbreak of COVID, monkeys and polio, America may not handle another addition well. “In general, we are not well prepared,” Li Zhou said.
At the same time, though, countries around the world have taken such different approaches to COVID mitigation that the pandemic may have further unrelated to the fate of flu season. Australia’s experience with influenza, for example, began, culminated and ended early this year; The new arrival of more relaxed travel policies likely played a role in the onset of the outbreak, before Bachelor’s degree rise 5 in the middle of the year Possibly precipitating the sudden drop. It is also unclear whether the United States might be in a better or worse position because of The last flu season He was cowardly, oddly shaped, and unusually late. South Africa also saw an unusual rise in influenza activity in the summer; That infection, Cohen told me, may have left new immunity dust and blunted the following season. But it’s always hard to know. “I was very strong in saying that I really think South Africa is going to have a tough season,” she said. “It seems I was wrong.” It could also be the long summer tail of the latest flu season in the northern hemisphere exacerbate The severity of the upcoming winter season, says John McCauley, director of the Global Influenza Center at the Francis Crick Institute in London. Viruses, kept out of season, may have an easier view from which to emerge this winter.
The crush of COVID has changed the dynamics of influenza in general, too. Webby tells me that the pandemic has “slashed” much of the diversity of the influenza virus population. Some strains may have completely disappeared. But others may also remain lagging and mutating, perhaps in animals or in uncontrolled pockets of the world. Lakdawala, of Emory, told me that these strains—which carry particularly great epidemic potential—can appear in the general population. And while the particular flu strains that are circulating avidly appear to be reasonably identical to this year’s vaccines, the dominant strains attacking the North could change, says Florian Kramer, an influenza virologist at the Icahn School of Medicine in Mount Sinai. Viruses also tend to shake and jump when they return from long vacations; It may take a season or two before the flu finds its usual rhythm.
Another epic variant of SARS-CoV-2 could crush a potential flu peak. flu cases Rise at the end of 2021The dreaded “epidemic” loomed. But then Omicron hit — and the flu essentially went away for a month and a half, Kramer told me, only returning to the scene after COVID cases declined. Some experts suspect that the immune system may have played a role in the work of this tag team: Although co-infection or sequential infection of SARS-CoV-2 and influenza viruses may occur, aggressive spread of the novel coronavirus variant may cause infection. persons. Defenses are on high alert, making it very difficult for other pathogens to gain a foothold.
Regardless of our odds of entering flu season, human behavior can still change the course of winter. One of the main reasons there have been no influenza viruses in the past few years is that mitigation measures have kept them away. “People understood transmission more than ever,” Lakdawala told me. Subbarao believes it is the wisdom of COVID that has helped keep Australian flu deaths low, despite the massive bulge in cases: Older people have noticed measures that thwarted the coronavirus and applied the same lessons to the flu. Perhaps residents of the northern hemisphere will behave in similar ways. “I hope we’ve already learned how to take infectious diseases more seriously,” McCauley told me.
But Webby isn’t sure he’s an optimist. “People have had enough of hearing about viruses in general,” he told me. The flu, unfortunately, doesn’t feel the same way about us.
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