There are other things you can do to stay healthy throughout the flu season, such as making sure to wash your hands consistently (which is one of the most crucial habits of people who never get sick). However, the single most effective line of defense against the flu is the flu vaccine. And unless you’re a very rare exception, you really should plan to get one.

Since the flu vaccine contains the influenza virus, there is a common misconception that the flu vaccine can give you the flu. This is a health myth you should stop believing — the flu vaccine cannot give you the flu. The viruses in the flu vaccine are either killed and inactivated or severely weakened. In both cases, the virus is unable to spread throughout the body and cause illness.

Your body’s immune response from vaccination actually dulls with time, meaning that last year’s flu shot just isn’t going to cut it for protecting you this year.

Another reason you need to receive the flu vaccine annually is because each year’s vaccine is different. Different strains of the flu virus are expected to be in circulation each year since the virus is constantly mutating and adapting. A team of over 100 national influenza centers in more than 100 countries keeps careful watch of the virus each year, testing thousands of flu virus samples. They send their findings to five World Health Organization (WHO) research centers that then consult the world’s leading scientists who specialize in the flu. Using this data, a new recommendation for the flu virus is made.

Before understanding more about how the flu vaccine is going to affect your body, it’s important to understand how the vaccine works. Essentially, the vaccine doses small amounts of either inactive or weakened influenza virus into your body. This process, called inoculation, triggers an immune response, and your body builds up antibodies to resist the strains of the virus included in the vaccine. Once these antibodies are generated, they remain in your system and work to ward off any future contact with the virus.

The process of developing antibodies to fight the flu takes time. It will take around two weeks from when you receive your vaccination until you are safeguarded against those strains of the flu. So if you come into contact with the flu before those two weeks are up, you can still get sick.

The CDC recommends getting vaccinated in early fall to ensure you’re safe before the start of flu season. The best time to get vaccinated is before the end of October. If you miss that deadline, you will still be able to get vaccinated since vaccines are often offered until January or later — you will just be at greater risk for infection until then.

That being said, there is a possibility of vaccinating too early. Jumping the gun can result in reduced protection against the flu later in the season. This is because your immunity declines over time and the earlier versions of the flu vaccine may not account for later mutations of the virus. That means July or August is too early.

You have a couple of options as to which vaccine to choose. Primarily, you may choose between trivalent and quadrivalent vaccines. Trivalent vaccines protect against three types of flu virus, while quadrivalent vaccines protect against an additional fourth. You may also opt for a high-dose option or a nasal spray vaccine that contains live, but weakened, strains of the virus. Ask your doctor about where the different types of vaccines are offered if you prefer one type over another.

There are some differences in the administration methods of these different types (the nasal spray, for instance, is obviously administered differently than an injection), but they are all considered equally effective. High-dose flu shots create a stronger immune response to the inactive virus, but that doesn’t necessarily correlate to better protection against future viruses. The most important thing is that you get the flu vaccine and that you choose one that is appropriate for your age group that doesn’t interfere with other health conditions.

The flu vaccine isn’t only for adults and school-aged children. In fact, the CDC recommends that everyone over the age of 6 months get vaccinated every year, with rare exceptions. Children as young as 6 months are not approved for receiving nasal spray vaccines, high-dose vaccines or recombinant vaccines (flu shots made without flu viruses or eggs, so they are safe for people with egg allergies). But children over 6 months should be vaccinated with an approved flu shot unless they have an allergy or other rare condition.

If you are over 65, it’s not advised to get a flu shot that’s administered with a jet injector. This is much less common than using a typical needle, but it can’t hurt to check with the person administering your vaccination that their choice is safe for you. You also should steer clear of the nasal spray vaccinations over the age of 50, which is something everyone over 50 should know about their health.

In addition to age restrictions, the CDC advises against nasal spray vaccines for certain populations. If you are pregnant, have a weakened immune system or have any of the other conditions listed on the CDC website, you’re better off opting for a regular flu shot. But remember, flu shots are considered just as effective as the spray.

Though it is rare, some people do experience severe allergic reactions to the flu shot. These people are likely either allergic to the virus itself or an ingredient in the vaccine such as gelatin or antibiotics. There has been some confusion about the safety of flu shots for people who are allergic to eggs. People with egg allergies can still get a flu shot, despite previous recommendations that they should steer clear and/or receive supervision for 30 minutes after receiving a vaccine. The CDC changed its recommendations after studies revealed how incredibly rare these reactions to the vaccine really were. For the rare case of a severe and life-threatening egg allergy, there are flu vaccines designed to be safe for these populations that can be taken with medical supervision.

The flu shot is considered generally safe for most of the population. However, you may experience some slight side effects. The CDC says that side effects include aches, a low-grade fever and soreness, redness or swelling where the shot was given. Though these side effects may be mildly uncomfortable, they don’t last long, often disappearing in a matter of days.

If you opt for a nasal spray vaccine rather than a shot, there are some additional side effects to consider. The viruses in the nasal spray vaccine are live but weakened. As a result, a small percentage of those who use it the nasal spray may experience mild symptoms such as a runny nose, headaches, a sore throat and a cough, and in children it may also cause wheezing, muscle aches and fever. These symptoms, however, are much milder than those of the actual flu and don’t last nearly as long.

It’s very, very rare that serious reactions to the flu vaccine occur. However, if you think you may have suffered health consequences after taking a flu shot, you can file for financial compensation. The National Vaccine Injury Compensation Program (VICP) accepts petitions from anyone who received a covered vaccine. If a case for injury is made or you are able to reach a settlement, you may be compensated accordingly.

There are many options for where your flu vaccination can take place. You could always visit your doctor’s office — or you could visit a pharmacy, a walk-in clinic, your local health department or a college health center. Also check if your employer or school offers vaccinations. HealthMap Vaccine Finder offers a tool for you to search by location and view vaccine opportunities in your area.

The flu vaccine can’t give you the flu — but that doesn’t mean you can’t still get sick. The flu vaccine does not provide 100% protection against the virus. This is in part because you can get sick within the 2-week window after getting your vaccine and in part because there is no way to include every current strain of the flu virus in the vaccination. Another mutation of the flu may still infect you.

Though the flu vaccine can’t entirely protect you from getting sick, it can reduce the severity of your illness if you are infected. A study from the CDC showed that hospitalized flu patients who received a flu vaccine had a lower risk of death, intensive care unit (ICU) admission and lengthy hospital admission. Rather than battling a life-threatening bout with the flu, you can ensure your case is mild if you do catch it by getting the vaccine. Should you get sick, at-home remedies can help you feel better. For instance, these are the best drinks to help fight the flu.

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