While it’s important to get vaccinated against the flu virus as early as possible, it’s never too late to reap the benefits of this vaccine. According to the U.S. Centers for Disease Control and Prevention, the peak months for the spread of the flu virus are January and February, and the season can last into mid-May.

Those at highest risk of complications from the flu are young children, people 65 and older, pregnant women and people with health conditions such as heart, lung or kidney disease, or a weakened immune system.

“Adults age 65 and older face the greatest risk of serious complications and even death as a result of influenza. That’s why it is so important that they get immunized. Even when older adults contract the flu after immunization, which can happen, those cases tend to be less severe and of shorter duration,” said Dr. Mark Lachs, director of geriatrics at New York-Presbyterian Hospital.

“It is important that all children get immunized against this illness,” said Dr. Gerald Loughlin, pediatrician-in-chief at the Phyllis and David Komansky Center for Children’s Health at New York-Presbyterian Hospital/Weill Cornell Medical Center.

Lachs and Loughlin offer the following guidelines to help protect these most vulnerable populations from catching the flu this winter:

1. It’s never too late: The flu season begins in the fall and can last through the spring, so if you didn’t get vaccinated in October you can still be immunized in December or January.

2. Know your options: A nasal vaccine is available for healthy children from age 2 and over, and for adults up to the age of 49. There are some restrictions, so check with your doctor.

3. Get your family members vaccinated: The CDC recommends the following groups get immunized against the flu every year: Children beginning at 6 months of age; pregnant women; people 50 years of age and older; people of any age with certain chronic medical conditions including asthma, diabetes, cardiovascular disease and any form of immunosuppressive illness; people who live in nursing homes and other long-term care facilities; people who live with or care for those at high risk for complications from flu, including health care workers; and household contacts and out-of-home caregivers of children less than 6 months, (children too young to be vaccinated).