Folks who want solid protection during the cold and flu season should get the influenza vaccine now, the U.S. Food and Drug Administration says.

The ideal time to get the flu vaccine is by the end of October, the FDA said in a news release.

“Flu viruses typically spread in fall and winter, with activity peaking between December and February,” the agency added. “Getting vaccinated in the fall can lower your chances of getting the flu.”

Each year’s flu vaccine targets the three influenza strains that are most likely to circulate and cause illness in the United States, the FDA said.

These strains are identified by watching flu trends in the southern hemisphere, where the wintertime cold and flu season is taking place while Americans are summering.

“The flu vaccine will trigger your immune system to produce antibodies to protect against influenza disease -- it will not make you sick with the flu,” the FDA added. “It can take about two weeks after vaccination for antibodies to develop in the body, which is an important reason to get your flu vaccine early, before flu activity starts.”

Folks need a flu shot each year because viruses mutate rapidly into new forms that attempt to evade previous immune protection, the agency explained.

In addition, the protection provided by an annual flu vaccine diminishes over time, and might be too low to prevent a person from catching the flu this season, the FDA added.

“Anyone can get sick with flu,” the FDA said. “Typically, children and people age 65 and older are most at risk of developing serious complications from influenza. In addition, pregnant people and those with certain chronic medical conditions are also most at risk of complications.”

The U.S. Centers for Disease Control and Prevention estimates that during the 2023-2024 U.S. flu season, there were:

• 35 million to 65 million flu illnesses

• 16 million to 30 million flu-related medical visits

• 390,000 to 830,000 flu-related hospitalizations

• 25,000 to 72,000 flu-related deaths

The CDC also estimates that thanks to the flu vaccine, Americans avoided:

• 6 million influenza-related illnesses

• 2.9 million influenza-associated medical visits

• 65,000 influenza-associated hospitalizations

• 3,700 influenza-associated deaths

Although now is the best time to get a flu shot, people can still benefit from it as fall turns to winter, the FDA said.

“If you have already been sick with the flu this season without getting vaccinated, getting a flu vaccine is still important because it helps prevent disease caused by three different strains of flu viruses,” the FDA added.

“You likely were infected with one type of flu virus strain, so the vaccine would offer protection against the strains that you haven’t already had,” the statement continued.