The US has an early flu season. In October, the Centers for Disease Control and Prevention noticed an increase in flu activity. In most of the country, the phenomenon is happening, but more intensely in the Southeast and south-central regions. The level of the virus continues to rise. According to the latest CDC flu report, 25 states have high or very high levels of outpatient visits for flu-like illness, which is characterized by a cough or sore throat.

The rise was four to six weeks earlier than usual according to William Schaffner. The season's early arrival was still surprising. He says that it was a big surprise to the experienced flu watchers that the season started so early.

Tennessee, where Schaffner is based, has a high level of respiratory illnesses. One third of the people who come in for urgent care at our medical center test positive for the flu. It shows a very wide spread. Over the past three weeks, Schaffner has seen an unprecedented increase in the number of patients who are hospitalized with the flu.

There have been over 2 million illnesses, 23,000 hospitalizations and 1,300 deaths from the flu so far this season, according to the CDC.

Chart shows number of positive flu tests in the U.S. reported to the WHO each week from January 2017 through October 2022.
Credit: Amanda Montañez; Source: FluNet/Global Influenza Surveillance and Response System at the World Health Organization (data)

Why Did the Flu Arrive So Early?

Experts don't know why the flu season started early. Predicting how bad the flu will be is not possible.

The flu disappeared in the U.S. in the early 2020s. According to the CDC, exposure to flu could affect immunity. The agency stated on its website in October that reduced population immunity could lead to a robust return of flu.

Arnold S. Monto is a professor of epidemiology at the University of Michigan. He says, "Now almost everybody is going around unmasked, so we have the situation whereflu transmission can go back to what we have normally seen." The spread of the flu may be aided by the fact that fewer people have immunity to the disease.

It is not true that lack of exposure to a virus impairs an individual's immune system. We have not had much experience with the flu for the last two years. That doesn't mean our immune system is weakened. We are able to fight off the virus and respond to the vaccine.

What Happened in the Past Two Years?

The low number of flu cases in the last two years is due to the implementation of preventive measures against COVID.

There are other factors that could have played a role. The director of the Center for Infectious Disease Research and Policy at the University of Minnesota said that the key to understanding why other respiratory viruses all but disappeared in 2020 and 2021 lies in how they interact with each other.

The ability of other respiratory pathogens to take off may be hampered by a seasonal virus. When the H1N1 flu epidemic hit in 2009, almost no one was practicing social distancing or masking. The H1N1 flu epidemic in France may have been delayed by the circulation of the human rhinoviruses. The H1N1 flu seems to have delayed the local wave of the respiratory syncytial virus.

You can sign up for Scientific American's newsletters.

In the Southeast and in south-central and north-central parts of the country, there has been a decrease in the number of respiratory syncytial virus cases. According to the director of the CDC's National Center for Immunization and Respiratory Diseases, it seems like the respiratory diseases are going down. Scientists are interested in studying how these Viruses interact with each other on a population level

What Can People Do to Protect Themselves?

Since the western and northwestern parts of the U.S. have not yet been affected by the flu, it is safe to assume that there will be plenty of flu transmission during November and December.

Experts say the most important thing to do is get a vaccine. Every person should get the flu vaccine, according to the CDC. A pregnant person is included. If you haven't gotten your shot yet, now is the time. The vaccine doesn't guarantee you won't get sick, experts say It greatly reduces the risk of illness and hospitalization. At Vaccines.gov, you can find information on vaccine sites. It is possible to get both shots at the same time.

More than 26 percent of adults have received a flu vaccine this fall, slightly higher than the estimated 23 percent at the same time last season, according to the Centers for Disease Control and Prevention. The most recent flu season before the Pandemic, when flu shot coverage was 29 percent in adults by the end of October, is similar to this year's.

Staying home when you have flu-like symptoms, covering your mouth and nose with a tissue when you cough or sneeze, and washing your hands often are additional ways to prevent the flu. masking might be considered again by people. Monto says that if people are in close proximity to each other, it is a good idea to mask. It is possible to prevent transmission of the flu with masks.

Regardless of how big or small the flu season is, the vaccine is still the best way to prevent severe disease. Schaffner says thatPredictions about flu are dangerous because they are so often wrong. We shouldn't try to predict whether or not to get vaccine. It's a good idea to get the vaccine every year.