A dangerous return of the flu in addition to COVID is expected this winter

A dangerous return of the flu in addition to COVID is expected this winter

A dreaded “twin demic” of influenza and COVID never happened last year, but the prospect of such a confluence this winter is resurfacing similar concerns among epidemiologists and other infectious disease experts. Flu cases began to rise in October and November, and those months saw a outbreak at the University of Michigan at Ann Arbor. These early signs suggest that, in the coming weeks, seasonal flu could wreak havoc, especially in hospitals, simultaneously with the national surge in the novel coronavirus, or SARS-CoV-2.

Public health officials agree that last year’s flu season was a no-show due to COVID mitigation measures, including less travel, more work from home, and remote education, use of mask and social distancing. Combined restrictions and limits on social interactions prevented flu from gaining ground, says lynnette brammer, team leader for the US Centers for Disease Control and Prevention for domestic influenza surveillance. This winter, many pandemic restrictions were relaxed or lifted entirely, creating an opportunity for influenza and other respiratory viruses.

Current flu infection rates almost match the CDC’s expectations for this time of year, says Brammer. “This looks like a regular start to a flu season,” she adds, noting that most outbreaks so far have been in young adults (particularly on college campuses) and that the virus is now spreading to older adults. . Influenza death rates in the US vary from season to season. The viral illness caused an estimated 20,000 deaths and 380,000 hospitalizations in 2019–2020. The most recent severe season, 2017-2018, is estimated to have killed 52,000 people and hospitalized 710,000.

Like COVID, flu can have serious long-term effects, says melissa andrew, associate professor of medicine at Dalhousie University in Nova Scotia. “Influenza is a major trigger for heart attacks and strokes. And in older people, it can cause delirium,” he says. Delirium, which is also a risk factor for dementia, can lead to cognitive decline and increase the risk of falls and hip fractures. “So it’s very important to remember not only the short-term impacts of an infection like influenza, but also the long-term ones,” says Andrew.

Speculation on the emergence of “flurone” as a single Frankenstein-like pathogen combining the viruses that cause influenza and COVID they are nonsense-but it is possible to develop flu and COVID infections at the same time. “Any of these diseases can be very bad in susceptible people, and if you put them together, it can only be worse. But we know very little about it,” he says. Eduardo belonged, director of the Center for Clinical Epidemiology and Population Health at the Marshfield Clinic in Wisconsin. “Sadly, we may find out this winter.”

Some looming concerns might be more about larger systems than individuals. Before the pandemic, hospitals and their emergency departments filled up annually during the winter viral season, Andrew says. “Now we are seeing hospitals overwhelmed with these waves of COVID, but everyone else needs their regular care too. If we have a wave of influenza on top of that,” he adds, “we could have a great trip.”

Even a mild flu season, Belongia says, could take an “already tipping-point health care system and tip it even further,” with severely ill flu patients competing for resources with very ill COVID patients.

An emerging trend signals a potentially severe flu season, Belongia says: During most seasons, influenza A subtypes dominate early and influenza B subtypes dominate late. Right now, she says, a subtype of influenza A called H3N2, which is causing almost all flu infections— is one that tends to dominate during the most severe flu seasons.

On a positive note, the flu seems to have returned without one of the four subtypes which normally circulate every season. One lineage of influenza B viruses, called the Yamagata, has been missing for almost two years. Unlike influenza A viruses, influenza B viruses almost exclusively infect humans, so researchers believe the Yamagata lineage may have extinct.

There’s another early sign of possibly milder outcomes: Current flu infections are floating around a bit above those seen in the 2015-2016 season, which had one of the lower death counts of influenza in the last nine years. Flu seasons vary greatly in their development, says Belongia.

Flu vaccination campaigns took a backseat to COVID-19 vaccines last fall. And while flu vaccine uptake is currently similar to last year in most of the country, it’s lower in some jurisdictions, according to the CDC. flu vaccination panel. Officials are most concerned about coverage among the most vulnerable groups, including children and pregnant people, whose vaccination rates are currently lower than at the same time last year. As of the end of October, just over a third of older adults with Medicare had been vaccinated, compared with 49 percent at the time in 2020 and 42 percent in 2019.

Manufacturers reformulate the flu vaccine each year to include the four viral strains that the World Health Organization and the US Food and Drug Administration require. anticipate will predominate in the next season. It is not yet clear whether this season’s vaccine strains will closely match the viruses that are circulating. A preliminary study from December 2021 identified changes in the currently circulating H3N2 strain that differ enough from the expected one used for this year’s influenza vaccine to potentially reduce the effectiveness of the shot

The slight mismatch is not surprising because the committees that selected the influenza strains for the vaccine had limited data on the most recent strains, a result of minimal influenza circulation for nearly two years, it says. Talaat Kawsarassociate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.

On top of that, flu vaccines have historically provided less protection against H3N2 than other strains, and H3N2 evolves faster than H1N1 and B strains, Talaat says. “But even in widely disparate years, being vaccinated still protects you from serious illness and hospitalization,” she adds. “So it’s still better than not being vaccinated.”

The flu season gap year in 2020-2021 may also have left our immune systems less prepared, setting us up for a more severe season this time around, some experts say. Typically each season, millions of people make antibodies after encountering that season’s flu strains. But much of that immune preparation didn’t happen last year.

“We have a population of people who are more susceptible and whose immune systems haven’t really seen a flu virus for a couple of years or more,” says Belongia. “In that setting, you want all the protection you can get and give your immune system a head start on the vaccine.”

Higher flu vaccination rates can also help reduce the burden on an already severely overburdened health care system, says Brammer. “That’s one of the many reasons we want to encourage people to get a flu shot,” she says.

It bears repeating that behaviors aimed at reducing the risk of a SARS-CoV-2 infection also help prevent the flu, says Talaat. “Do the things that we know work against all of these viruses,” she adds. That means making sure you’ve had your COVID and flu shots and, if eligible, your COVID booster shot and pneumonia shot, Talaat says. the CDC pneumonia vaccine recommended adults 65 years of age or older and children under two years of age, as well as other people with certain medical conditions.

Although the flu is not as contagious as SARS-CoV-2, social distancing and the use of masks still reduce flu transmission, as does frequent and meticulous hand hygiene. If people develop the common symptoms of flu and COVID (such as fever, cough, congestion, and body aches), most clinics can test for COVID and flu at the same time. The main reason to test for the flu is to treat it with antivirals and thus reduce the risk of severe illness, hospitalization and death, says Brammer.

If nothing else, like the past two years, the 2021-2022 flu season will be a learning experience. “Just like COVID, no one really knows what’s going to happen next” because the last six months alone have been unprecedented, says Belongia. “It’s really given us a lot of humility that despite all our knowledge of immunology and virology, no one really had any idea what was going to happen next.”

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