Vaccine Basics

Why Are Vaccines Important?

Measles, mumps, and whooping cough may seem like quaint old illnesses confined to 19th century novels. But more and more teens are being exposed to them, especially in schools and on college campuses where large numbers of people are together in close quarters.

Diseases like measles, which were on their way out in the United States, are making a comeback as they are brought in from other countries by travelers. These diseases wouldn't spread as quickly — or be as serious — if everyone were vaccinated against them. But many people aren't.

It's not your fault if you didn’t get all the vaccines you need. Recommendations change and new vaccines get developed. So you may not have gotten some when you were younger.

Some vaccines (like the HPV vaccine) are given as a series of shots, not just one single dose. Some people may have missed getting all the required shots. Not getting a full course of a vaccine leaves a person unprotected and still at risk for getting a disease. Other vaccines require a booster shot later to ensure that the level of immunity remains high.

Which Vaccines Do I Need?

Doctors recommend getting vaccinated against these diseases:

• diphtheria, tetanus, and pertussis (Tdap vaccine)
• measles, mumps, rubella (the MMR vaccine)
• hepatitis A
• hepatitis B
• meningococcal disease (e.g., meningitis)
• human papillomavirus (HPV) infection (which can cause genital warts and different types of cancer)
• varicella (chickenpox) if you have not had the disease
• polio
• flu (influenza)
• COVID-19

You can still get a shot if you've missed it. If you've missed some shots in a series of vaccines, you don't need to get the whole series again — you can simply pick up where you left off.

Some people may need other vaccines. For example, people with diseases that affect their immune system (like diabetes, HIV infection, or cancer) should get a pneumococcal vaccine. People who live in areas where dengue is common need a dengue vaccine after they’ve had dengue fever. People who travel abroad may need to get special vaccines, depending on which country they'll be in. Vaccines can take about 2 weeks to start working, so ask your doctor ahead of time which ones you'll need. If you're pregnant, ask your doctor if there are any vaccines you should get.

How Do I Find Out if I've Had the Right Vaccines?

Ask a parent to contact your pediatrician or family doctor so they can check your health records.

Get a certificate from your doctor showing that you've had all your shots, and keep it where you can find it easily later. If you plan to go to college, you'll need to show proof that you've had a condition or been vaccinated. Some jobs also require proof of vaccination — for example, if you want to work or volunteer in a hospital.

Because you may have missed getting certain shots, this is one of those times when you need to take charge of your health: Bring up vaccines when you see your doctor and ask if you've had all the recommended ones.

What Are the Possible Side Effects of Vaccines?

Like any medicine, vaccines may cause side effects, but getting one is far safer than getting the disease it prevents. The most common reactions include soreness, redness, and swelling in the area of the shot or a low fever. Taking acetaminophen or ibuprofen usually helps with these side effects. Some people feel dizzy or even faint after getting a vaccine. If this has happened to you, it might help to eat or drink before getting a shot and then sit or lie down for 15 minutes afterward.

It's rare to have any kind of bad reaction to a vaccine. If you've had reactions to vaccines in the past, let your doctor know. Before getting a vaccine, discuss any concerns that you have about it with your doctor.

Who Should Not Be Vaccinated?

People who have a weak immune system (from AIDS or some cancers, for example) should talk to their doctors before getting vaccinated. This is also true for those who receive treatments like chemotherapy or who take medicine that can weaken the immune system. Pregnant women can benefit from some vaccines (like Tdap, the flu shot, and RSV vaccine) but should talk to a doctor or health clinic before getting vaccinated.

What Else Should I Know?

We usually think of vaccines as shots, but not all vaccines are given that way. Some are given orally (by mouth) or in other forms like nasal sprays.

Still, some vaccines are just best given as shots. And it's completely normal to feel nervous about them. If you're one of the many people who dread shots, you can try a few things to make shots easier, like taking calming breaths and even coughing as the needle goes in.

The good news is that the shot itself only lasts for a second, but you'll be protected for a long, long time after that!