Still Need Your Flu Shot? Here's What to Know - CNET

Protection from flu vaccines takes a couple of weeks to kick in, so getting one now may protect you ahead of the holidays.

One of the best ways to prepare for cooler-weather health problems is to make sure you're up to date on vaccines that can help protect against respiratory viruses, which includes the flu.

Each year, scientists and doctors decide on which strains of influenza are most likely to circulate and make people sick during flu season, which typically peaks between December and February but begins during fall. The makeup of the 2024 to 2025 flu vaccines has been decided, and pharmacies across the country should have them in stock.

Doctors and health officials typically start recommending the flu vaccine in September, but if you haven't gotten yours yet, it's definitely not too late. In fact, waiting until now means that you still have time to get vaccinated before flu activity typically starts to pick up and before the bulk of holiday gatherings, which offer respiratory viruses such as flu, COVID and RSV an opportunity to circulate more easily.

Here's what to know about this year's flu shot. Also, here's which vaccines you should keep in mind if you're 50 or older.

Nearly everyone aged six months or older should get a flu vaccine, according to the CDC.

The CDC offers rare exceptions for who shouldn't get one, including people who've had a severe allergic reaction to a flu vaccine in the past, those who have a severe allergy to an ingredient in the flu vaccine (like gelatin) and those with a history of Guillain-Barré Syndrome, a type of paralyzing illness.

The flu vaccines that will be available this season are egg-based and cell- or recombinant-based, according to the CDC.

Older adults in their 60s and up have historically been recommended a higher-dose vaccine since severe illness is more common in older adults.

Dr. Amesh Adalja, an infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security, said in an email that older adults should opt for a "high-dose" or "adjuvanted" vaccine.

Besides age-based recommendations, people who are pregnant traditionally haven't been recommended the nasal spray flu vaccine, along with other adults aged 50 and up.

One more significant change this year so far is that vaccines will be trivalent, meaning they'll target three different strains of flu. This is a shift away from quadrivalent vaccines (four strains) because a specific type of flu (influenza B/Yamagata viruses) hasn't been around since March 2020.

Recently, the FDA approved the very first at-home flu vaccine, for adults under age 50 and children 2 and older. It's a nasal vaccine you'll get a prescription for through an online pharmacy, but unfortunately, it's not expected to be available until next year's flu season.

Flu vaccines are generally recommended starting in September or October, though you can get it any time after that. In general, it takes about two weeks after you get the flu shot for your body to build up an immune response and offer protection.

So, getting it now or in early November means that the vaccine should be fully "kicked in" by Thanksgiving time, which in the US marks many people's first indoor, close-quartered gathering (i.e., the big opportunities for respiratory viruses to spread more easily).

Waiting until at least October may also mean you'll have protection toward the end of peak flu season, which typically stretches into spring.

"Getting it [too early] may lead to decreased protection at the tail end of the season," Adalja said in late August, adding that he recommends people wait until October to get the flu vaccine.