What type of flu shot is best for people over age 65

• Seniors are at higher risk of severe complications from the flu and need specialized flu vaccines.
• Seniors can get a standard flu shot but will likely not be as well protected.
• Two flu shots for seniors include the high dose vaccine and the adjuvanted inactivated flu shot.

People over the age of 65 are at greater risk of developing serious complications, like pneumonia, from the flu. That's why it's very important that seniors get the flu shot each year to prepare themselves for the dreaded fall-winter flu season.

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However, the typical flu shot may not be as effective for seniors, says Laura Haynes, PhD, a professor of immunology at the University of Connecticut Center on Aging.

If a normal flu shot is available, it's better than nothing. But people over the age of 65 typically have a weaker immune system due to age and therefore should get one of the specialized vaccines so they are equally protected against the flu and severe complications that could lead to hospitalization.

Types of flu shots for seniors

There are two types of flu vaccines that the CDC recommends for people over 65:

1. High dose flu vaccine, also called Fluzone
2. Adjuvanted inactivated flu vaccine, known as Fluad

You can get both the high-dose and adjuvanted flu vaccines at your doctor's office, but you can also usually find the high dose vaccine at pharmacy clinics like CVS.

There haven't been any studies comparing the high-dose and adjuvanted flu vaccines, and the CDC doesn't state any preference about which vaccine to use. However, some doctors may prefer the high-dose vaccine because it has been in use since 2009, while the adjuvanted vaccine came out more recently in 2015.

High dose flu vaccine

The high dose flu vaccine has four times as many antigens as a regular flu shot, and is available specifically for people over 65.

Medical term: Antigens are pathogenic molecules that trigger the immune system to release antibodies designed to fight infection. Vaccines contain antigens in order to alert the immune system to specific pathogens, like the flu virus, so that it's more equipped to fight those pathogens if they later invade your body.

The higher antigen load means that even if your immune system has a weaker reaction, having more virus particles present helps your body create more antibodies - ideally enough to protect you from infection, Haynes says.

A study published in 2014 found that the high dose flu vaccine was 24% more effective in preventing flu in people over 65, compared with the standard vaccine. Moreover, seniors who get the high dose vaccine are also less likely to be hospitalized for the flu.

Adjuvanted inactivated flu vaccine

Another vaccine specifically designed for seniors is the adjuvanted, inactivated flu vaccine. An adjuvant is a substance that increases your body's reaction to virus proteins.

Medical term: Inactivated flu shots contain dead flu viruses. The antigens in the vaccine still provoke an immune response so you build up antibodies against the flu virus. Inactivated flu vaccines are typically recommended for people who are pregnant, are over the age of 65, or who have certain medical conditions.

The substance added to the adjuvanted flu vaccine is squalene oil, also called MF59, which is found naturally in plants and animals. "This gives an extra boost to the immune response to the vaccine which will then lead to greater protection from infection," Haynes says.

Because the adjuvanted vaccine spikes your immune response, it may also have more side effects than the standard vaccine, including irritation at the injection site, muscle aches, and headache. However, the vaccine offers great protection for seniors - a 2020 study found that people over 65 who got the adjuvanted vaccine were less likely to be hospitalized for the flu, compared with those who got the standard vaccine.

Insider's takeaway

Getting any flu shot is helpful for seniors, but the high dose and adjuvanted flu shots are the best option to guard against illness and hospitalization.

There is also little risk involved with getting the flu vaccine. "You cannot get the flu from a flu vaccine," Haynes says, though you may not feel well for a day or two after getting it because your immune system is gearing up to fight off the virus, which can cause mild symptoms like headache or low-grade fever.

The CDC recommends that any adult can get the flu vaccine unless you have a severe allergy to one of the ingredients, like gelatin or certain antibiotics. If you aren't sure which flu vaccine is right for you, talk to your doctor to figure out the best option.

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