Fall is usually the time of year when we start wearing the warm sweaters and drinking the hot drinks. At the same time, the flu is coming. Most people haven't had the flu in the past few years because of the pandemic.

During the 2020 and 2021 flu seasons, the disease was "unusually rare," according to the United States Centers for Disease Control and Prevention. This is thanks to safety measures to protect against covid-19, such as wearing masks, washing hands more often and staying at home.

But since life is starting to return to normal for many, the number of people suffering from the flu is expected to be higher this fall and winter, so experts recommend getting vaccinated against the flu.

But when exactly should you get vaccinated? And is it possible to get a flu shot at the same time as the "booster" against Omicron? Here is what the experts say Yahoo Life.

Why should you get a flu shot every year?

The flu is actually caused by several different viruses. The two most common are the influenza A virus and the influenza B virus, and each has its own subtypes and groups.

Because flu viruses are constantly changing and because immunity declines over time, the flu vaccine is changed each year to provide better protection. There is even an organization, the World Health Organization's Global Influenza Surveillance and Control System (GISRS), founded in 1952, that tracks the frequent changes in the flu virus.

Dr. Petro Piedra, professor of molecular biology, microbiology and pediatrics at Baylor School of Medicine, says it's "a good global surveillance network that tracks which viruses are circulating and then makes a best guess at what needs to be changed in the vaccine."

Dr. Piedra explains that the vaccine is usually an "almost perfect match" to one of the circulating viruses.

"It is always difficult to have a perfect vaccine for all the viruses that are circulating. But you don't always have to have a perfect vaccine to get cross-protection" - says Doctor Piedra.

How effective is the flu vaccine?

Flu shots have been shown to reduce the risk of seeing a doctor for the flu by 40 to 60 percent, according to the United States Centers for Disease Control and Prevention.

"The flu vaccine reduces the risk of severe flu symptoms, hospitalization, hospital admission, and death," says Dr. Riza Conroy, a family medicine physician at The Ohio State University Wexner Medical Center.

The vaccine can also help protect those most prone to complications from the flu virus, which typically affects children ages 6 months to five years, as well as those over 65, according to the Mayo Clinic.

The United States Centers for Disease Control and Prevention claims that flu shots can save children's lives. A 2022 study found that the flu vaccine in children reduces the risk of life-threatening flu by 75 percent.

"Children can also die from the flu," emphasized Dr. Piedra. "In general, children who died from the flu were not vaccinated. He adds that not only elderly people die from the flu. "Children have a higher risk of more severe complications, as do pregnant women.

When is the best time to get vaccinated?

Although influenza viruses are detected throughout the year, they circulate more in the fall and winter.

Conroy points out that the peak of the flu season is "from December to February, but an increase in the number of patients is also observed around March, and it is possible until May."

In his opinion, "the best time to get a flu shot is around October," so you're protected during flu season. He notes that the vaccine "usually works best two weeks after vaccination." Peidra agrees that October is a "good month" for vaccination. The flu vaccine is effective for about five to six months, Conroy noted.

Who should be vaccinated against the seasonal flu?

Everyone over the age of six months should get an age-appropriate flu shot, Conroy said, unless their doctor advises them otherwise based on general health.

According to the United States Centers for Disease Control and Prevention, there are several flu vaccines approved for children six months of age and older, and two for those over 65 years of age.