Why did this year’s flu season start so early?

The US flu season has arrived much earlier than usual. The Centers for Disease Control and Prevention first discovered early rise Influenza activity in mid-October. Officials said the phenomenon is occurring in most of the country, but is occurring more intensely in the southeastern and central-southern regions.A month later, virus levels continue to rise sharply. According to the latest CDC flu report, 25 states or jurisdictions now have the flu. high or very high Number of outpatients with flu-like illness characterized by cough and sore throat in addition to fever.

William Schaffner, a professor and infectious disease expert at Vanderbilt University School of Medicine, said it rose four to six weeks earlier than normal. was outside. “It was a huge surprise, even for experienced flu watchers, that the flu emerged, increased dramatically, and became so widespread so early in the season,” he says.

Schaffner’s home state of Tennessee has one of the highest levels of respiratory disease at this time. “At our medical center’s emergency care clinic, her one-third of the people who came in tested positive for the flu,” says Schaffner. “This is huge and indicates that it is very widespread.” Schaffner also observed an unprecedented increase in the number of patients in his clinic hospitalized with the flu in the past three weeks. .

of Estimation of CDC At least 2.8 million people have fallen ill, 23,000 have been hospitalized and 1,300 have died from the flu so far this season.

Why did the flu come so early?

The reasons behind the early flu season aren’t entirely clear, according to experts. Nor can we predict how severe this season’s flu will be.

flu is almost gone 2020-2021 coincided with the COVID pandemic in the United States.this Lack of flu exposure It may have affected immunity, according to the CDC. “With weakened population immunity, especially among young children who have never had the flu or been vaccinated, the flu could certainly recur,” officials said on their website in October. Stated.

“Population-level immunity is usually important in terms of how many infections we see in a given season,” says Arnold S. Montt, professor of epidemiology at the University of Michigan School of Public Health. “Now most people are walking around with their masks off. [flu] Infection can return to what we normally see,” he says. He added that the fact that fewer people now have antibodies to the flu because they weren’t exposed to it during the pandemic may be helping the virus spread.

This does not mean that lack of exposure to the virus will compromise an individual’s immune system. This is a misconception sometimes called “immune debt”. “Yes, we’ve experienced less flu viruses in the last two seasons. But that doesn’t mean that our immune systems are somehow weakened,” says Schaffner. We are fully capable of fighting it off and responding to vaccines.”

What happened in the last two years?

The decline in flu cases over the past two years has often been attributed to the implementation of precautionary measures against COVID, such as masks and social distancing practices.

These actions may have played an important role, but other factors may have played a role, according to epidemiologist Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota (CIDRAP). , the key to understanding why other respiratory viruses have all but disappeared in 2020 and 2021 lies in how these viruses interact with each other.

“In the past, we’ve learned that circulating seasonal viruses can weaken the ability of other viral respiratory pathogens to take off,” says Osterholm. His one example of this phenomenon, known as viral interference, dates back to his H1N1 flu pandemic in 2009. Researchers believe that a type of cold virus called human rhinovirus (HRV) may be circulating in France. delayed H1N1 Influenza that is prevalent in the country. continue, H1N1 seems delayed The next localized wave of a common virus known as respiratory syncytial virus (RSV). (RSV surges again The United States paused in the first year of the COVID pandemic, after a significant peak in cases in the summer of 2021.)

Although RSV is still on the rise nationwide, recent reports indicate that it has recently started to decline in the southeast, and in the central and central north of the country. CDC media briefing“In these three regions, RSV appears to be on the decline and influenza is beginning to rise or surge,” said José R. Romero, director of the CDC’s National Center for Immunization and Respiratory Diseases, briefing. said in How these viruses interact at the population level is still poorly understood, but scientists are increasingly interested in studying this kind of interference.

What can people do to protect themselves?

While it’s impossible to predict what the 2022-2023 flu season will be like, Schaffner said the western and northwestern U.S. has yet to see the spread of the virus, so it’s likely that the flu season will continue to spread through November and December. He said it is safe to assume that a large number of influenza infections will occur. affect a wide range.

Experts say the most important thing people can do to protect themselves from the flu is to get vaccinated. The CDC recommends that everyone 6 months of age and older get the flu vaccine annually.For that pregnant personWith cases rising, now is the time to get vaccinated if you haven’t already. Experts point out that vaccines don’t guarantee you won’t get infected. COVID vaccine, significantly reducing the risk of serious illness and hospitalization.Get information about flu and COVID Vaccines.gov Immunization SiteIt’s also safe to get both shots at the same appointment.

CDC estimates that as of mid-October, more than 26% of adults had vaccinated against influenza This fall will be slightly higher than the estimated 23% for the same period last season. This level of coverage is similar to the most recent pre-pandemic flu season, when adult flu vaccination coverage was 29% of his by the end of October 2019, according to the CDC.

addition Habits to prevent flu Avoid close contact with sick people, stay home when you have symptoms, cover your mouth and nose with a tissue when coughing or sneezing, and wash your hands frequently. No. “If you’re in a venue where people are close to each other, wearing a mask is never a bad idea,” says Monto. “Masks prevent not only COVID but also influenza transmission.”

But vaccination remains the gold standard for preventing serious illness, no matter how big or small the flu season is. because they are,” says Schaffner. “This is not what we’re trying to predict. [to get] vaccinated. Get vaccinated every year. “