While the Centers for Disease Control and Prevention recommends getting the seasonal flu vaccine as soon as possible, some doctors say people should wait until October or November. When's the best time to get the flu shot?

"Everyone should get the flu vaccine as soon as it becomes available in their community," CDC spokesman Tom Skinner told Life's Little Mysteries. "In the United States, the vaccine starts to become availablein August and September."

And because the vaccine is already on hand at clinics and stores in most towns and cities, the time is now, Skinner said. The vaccine provides six to eight months of protection, and the ever-unpredictable flu season can begin as early as October.

When will flu season peak?

However, experts in some regions are able to calculate approximately when the "peak" flu season will hit their locations, based on records offlu cases in previous years. For example, the flu season in Marion County, Ind., tends to peak in February and March, with cases of the illness tapering off in April, according to Marion County Health Department spokesman John T. Althardt.

The department, therefore, offers flu shots to Marion County and Indianapolis-area residents from October to December, Althardt said.

"For residents of  these areas, that's the most effective time to getvaccinated," he told Life's Little Mysteries. Although the Marion County Health Department made their flu shots available later than medical centers in most other states this year, Althardt stressed they do not discourage people from getting vaccinated earlier if they want to.

In fact, there are no drawbacks to getting vaccinated early. While some fear getting the shot (or spray) in August or September may cause the vaccine's effectiveness to wane toward the end of the flu season, the CDC assures that this is not the case. The shot provides protection against the influenza strains contained in the vaccine for the entire season, the CDC said.

The three strains in the shot vary from year to year, and are decidedupon by the World Health Organization (WHO), which collects worldwide data on which viruses pose the largest threat, according to the CDC. TheU.S. Food and Drug Administration helps to select the strains. This year's vaccine includes protection against the 2009 H1N1 virus, the CDC said.

Yearly shot recommended

Because the virus circulates the globe constantly and evolves, it's important to get a shot every year, said Neil Fishman, director of the department of healthcare epidemiology and infection control at the University of Pennsylvania.

A vaccinated person's immunity declines after a year, so last year's flu shot may not protect them this season, according to the CDC. And thevaccine cannot protect against all flu strains, so people who get the shot should still take proper hygienic precautions, such as frequently washing their hands.

But it's never too late to get the vaccine, the CDC said. Even vaccinations in late November or December may help, because the flu usually peaks in January or February. However, it's difficult to predictwhen the season will peak.

Why flu season peak times vary across the country remains unknown, though temperature and climate conditions may play a role, Fishman said.

"Everyyear, it's a guess as to when flu season will peak in different geographical areas, and you can't always predict when it will peak – in January, February or March," Fishman added. "The only thing that can be predicted about the flu is that it's unpredictable."