NEW YORK (Reuters Health) - Flu season may be closing in, but it’s not too late to avert the misery by getting a flu shot.Though flu season can kick off as early as October, it typically peaks around February in the US — meaning there’s still plenty of time to get vaccinated.

People can get the shot as late as December and still be protected, said Dr. Daniel A. Hussar of the Philadelphia College of Pharmacy at the University of the Sciences. Still, he advises against procrastination; for optimal protection, Hussar told Reuters Health, “sooner is better than later, in my opinion.”

Up to 20 percent of Americans come down with influenza each year. For most people, the virus causes temporary misery — including fever, sore throat, aches and pains — but for some it can lead to potentially deadly complications like pneumonia.

The elderly and people with chronic conditions like heart disease, asthma and diabetes are among those at risk of complications. Health officials advise certain groups to get a flu shot every year: adults age 50 and older; pregnant women; children between the ages of six months and five years; and anyone with a medical condition that raises the risk of complications.

It’s also best for people who are around high-risk individuals — like daycare workers and parents of young children — to get vaccinated, Hussar said. Health care professionals who have contact with patients should be vaccinated as well. He considers the flu shot a “wise investment” for anyone who’d rather not be sidelined by the illness for several days. And unlike in some seasons past, Hussar noted, it appears there will be an adequate supply of vaccine doses on the US market this year.

So, he said, healthy people shouldn’t worry about “taking” a dose from someone who needs it more. The flu shot doesn’t provide airtight protection, however.

A research review published just last week questioned the value of flu shots, saying there’s no evidence that vaccination has reduced the major burdens of the illness, including hospitalisations and deaths.

Still, experts say the vaccine protects against infection in most recipients. In general, the flu shot is about 75 percent effective, Hussar said, though it’s slightly less effective in the elderly. This is probably related to changes in immune function that come with age, he noted.