The flu is a contagious respiratory illness that can cause a variety of symptoms. Some of these symptoms include coughing, sore throat, body aches, fatigue, chills, and runny nose.

The flu can strike in the fall, winter, or spring, although outbreaks tend to peak between December and February. Some people who get the flu recover in about one to two weeks without major complications.

In seniors — those ages 65 and older — the flu can cause life-threatening complications. This is why it’s important for older adults to get an annual flu shot.

Here’s what you need to know about flu shots for seniors, including the types and reasons to get one.

The seasonal flu shot is approved for most people ages 6 months and older. The shot is typically injected into the arm, either in a muscle or underneath the skin.

It’s important to understand that flu shots aren’t one-size-fits-all. There are different types of flu shots, and some are specific for different age groups.

If you’re a senior and considering getting a flu shot this season, chances are your doctor will recommend a flu shot designed specifically for people ages 65 and older.

One type of flu vaccine for older adults is called Fluzone. This is a high-dose trivalent vaccine. A trivalent vaccine protects against three strains of the virus: influenza A [H1N1], influenza A [H3N2], and the influenza B virus.

The flu vaccine works by stimulating the production of antibodies in your body that can protect against the flu virus. Antigens are the components that stimulate the production of these antibodies.

A high-dose vaccine is designed to strengthen the immune system response in older adults, thus lowering the risk of infection.

Another flu vaccine is Fluad, a standard-dose trivalent shot made with adjuvant. Adjuvant is another ingredient that produces a stronger immune system response. It’s also designed specifically for people ages 65 and older.

In addition to the trivalent flu vaccine, there are also quadrivalent flu vaccines. These vaccines protect against four different strains of the virus: two influenza A viruses and two influenza B viruses.

There isn’t a quadrivalent flu shot designed specifically for seniors. But some versions of the vaccine are approved for use in multiple age groups, which includes people over the age of 65.

If you’re getting the flu vaccine, you may wonder whether one option is better than others. There haven’t been any studies comparing the high-dose and adjuvant flu vaccines for older adults, so either option can help protect you from the flu.

For the most part, the flu vaccine is safe. But you shouldn’t get a flu shot if you’ve already had a severe allergic reaction to the vaccine, including breathing difficulty, wheezing, or dizziness.

It’s not unusual to experience mild flu-like symptoms after a vaccination. These symptoms tend to disappear after one to two days. Other common side effects of the vaccine include soreness and redness at the injection site.

You may have concerns about the cost of getting an annual flu vaccination. The cost varies depending on where you go and if you have insurance. In some cases, you may be able to get the flu shot free of charge or at a low cost.

Ask your doctor about getting the flu shot during an office visit. In addition, some pharmacies and hospitals in your community may provide vaccinations. You can also research flu clinics at community centers or senior centers.

Use websites like Vaccine Finder to find the closest location near you that offers the flu vaccine, and contact them to compare costs.

The sooner you get a vaccination, the better. On average, it can take up to two weeks for your body to produce antibodies to protect against the flu. The Centers for Disease Control and Prevention recommends getting a flu shot by the end of October.

The flu shot is especially important for older adults because they tend to have a weaker immune system.

When the immune system isn’t strong, it becomes harder for the body to fight off infections. Likewise, a weaker immune system can lead to flu-related complications. Secondary infections that can develop with the flu include ear infections, sinus infections, bronchitis, and pneumonia.

People ages 65 and older are at higher risk for serious complications. In fact, it’s estimated that as many as 85 percent of seasonal flu-related deaths occur in people ages 65 and older. Plus, up to 70 percent of seasonal flu-related hospitalizations occur in people ages 65 and older.

On average, the flu shot offers about 40 to 60 percent protection against the virus. If you become ill after getting a vaccination, a flu shot may lessen the severity of symptoms and shorten the duration of the illness.

The flu is a potentially serious viral infection, particularly in people ages 65 and older.

To protect yourself, ask your doctor about getting a high-dose flu vaccination. Ideally, you should get a vaccine early in the season.

Keep in mind that flu strains vary from year to year, so be prepared to update your vaccination next flu season.