Ask CDC – Vaccines & Immunizations

Is there any danger from receiving extra doses of a vaccine?

Most of the time, your risk of serious side effects does not increase if you get extra doses of a vaccine. Getting extra doses of oral vaccines, such as rotavirus or typhoid, is not known to cause any problems. The risk of a reaction at the injection site following certain injected vaccines, such as DTaP (diphtheria, tetanus, and pertussis) or pneumococcal vaccine, increases if the doses are not separated by the recommended amounts of time. In these cases, it is the spacing of the doses, not the number of doses, that creates the risk. These reactions can be unpleasant, but they are not life-threatening. Any serious reaction following vaccination should be reported to the Vaccine Adverse Event Reporting System (VAERS).

Are you a healthcare provider?


  • Call 1-800-CDC-INFO now and follow the prompts to be connected with an agent (during normal business hours)

CDC Publications

Parents’ Guide to Childhood Immunizations

CDC Resources

Advisory Committee on Immunization Practices (ACIP) Recommendations

Parents’ Guide to Childhood Immunizations

External Resources

The National Medication Errors Reporting Program (ISMP MERP)
Institute for Safe Medication Practices

Vaccine Safety: Dosing Safety: Children’s Hospital of Philadelphia

Do I or my child have to start over if we have missed vaccine doses?

There is no need to restart a vaccine series no matter how much time passed between doses. You can view and print the childhood vaccine schedule from the Vaccines and Immunizations section of CDC’s Website.

CDC Resources

General Best Practice Guidelines for Immunization

Immunization Schedules

Who should get the Tdap vaccine?
a pregnant woman speaking to a healthcare professional

CDC recommends Tdap (the tetanus, diphtheria, and whooping cough vaccine) for:

  • Preteens and teens,
  • Pregnant women, and
  • Adults who have never received the vaccine.

Preteens should get one dose between the ages of 11 and 12 years. Teens who didn’t get Tdap as a preteen should get one dose the next time they visit their doctor.

If you are pregnant, you should get Tdap during each pregnancy. After you get the shot, your body creates protective antibodies and passes some of them to your baby before birth. These antibodies give your baby some short-term protection against whooping cough in early life.

Are you a healthcare provider?

Do you have questions about who should receive Tdap? See the Summary of Pertussis Vaccine Recommendations.

Adults should get one dose of the tetanus and diphtheria (Td) vaccine every 10 years. However, CDC recommends adults get one dose of Tdap in place of a Td dose if they have never received Tdap. By doing so, adults boost their protection against whooping cough. Tdap can be given no matter when you got your last Td vaccine.

Be sure to ask your doctor any questions you have about whether you or your family should get certain shots. Your doctor will make you aware of any reasons you should not get the vaccine.

For more detailed information about Tdap vaccine, call 1-800-CDC-INFO and follow the prompts to be connected with an agent (during normal business hours).

CDC Resources

What Everyone Should Know about Diphtheria, Tetanus, and Whooping Cough Vaccination

Tdap Vaccine Information Statement (Tdap Vaccine: What You Need to Know)

CDC’s Pregnancy and Whooping Cough Website

Where can I get a copy of my (or my child’s) immunization or vaccine records?
Image of doctor holding a clipboard

CDC does not store personal vaccination records. There is not a national organization that maintains vaccination records. Some doctors, schools, and communities might use registries (or “Immunization Information Systems”) to keep track of vaccinations. However, most often, the only existing records are the ones you or your parents were given when the vaccines were administered, or those in the medical record of the doctor or clinic where the vaccines were given.

If you’re having a hard time finding your or your child’s vaccine records, contact:

  • The doctor(s) or clinic (s) where you or your child got vaccinated,
  • Schools or student health centers, or
  • Your local or state health department.

Keep in mind that doctor’s offices, clinics, and schools only keep vaccine records for a few years.

You should also check family records, such as baby books or military records.

If you still can’t find the vaccine records, you or your child may need to:

  • Repeat some of the vaccines, or
  • Get a blood test to find out if you are immune to (protected from) certain diseases.

CDC Resources

Recommendations and Guidelines: Vaccination Records: Finding, Interpreting, and Recording

External Resources

Vaccine Administration Record for Children and Teens, March 2011
Immunization Action Coalition

Tips for Finding Vaccine Records
Immunization Action Coalition

What is the Vaccine Adverse Event Reporting System (VAERS)?

The Vaccine Adverse Event Reporting System (VAERS) is a program that allows healthcare providers or their patients to report any health problems that occur after a vaccination.

VAERS analyzes information from these reports and looks for patterns. If it appears that a particular problem might be linked to a vaccine, experts will work to determine whether the vaccine might be causing the problem, or whether it occurred following the vaccination by chance. If the link appears to be real, CDC might recommend new precautions for the vaccine. In extremely rare circumstances, a vaccine could be removed from the market.

It’s important to remember that a report to VAERS does not prove that a problem was caused by a vaccine—only that the problem occurred after the vaccination. In fact, many of the problems reported to VAERS are found not to have been caused by vaccines. But VAERS helps CDC and FDA know when a possible problem needs to be looked at more closely.

To learn more about VAERS, or how to report an adverse event, you can visit the VAERS website or call them directly at 1-800-822-7967.

CDC Resources

VAERS: Frequently Asked Questions

VAERS: Vaccine Adverse Event Reporting System

Vaccine Safety and Adverse Events: At A Glance

Vaccines and Immunizations

How to report an adverse event

CDC Publications

Do Your Part for Vaccine Safety: Report to VAERS
Centers for Disease Control and Prevention and the U.S. Food and Drug Administration

Who should get the rabies vaccine?

The rabies vaccine may be given to a person after possibly coming into contact with the rabies virus. But as a safety measure, some people should get the shot before they get exposed, including people who are at high risk of coming into contact with the virus, such as:

  • Veterinarians,
  • Animal handlers,
  • People who work in a lab where rabies is present,
  • People who often explore caves where there are bats,
  • People who work with the rabies virus, and
  • People who travel to parts of the world where rabies is common.

If you, or someone you know, has been bitten by a mammal—such as a dog, cat, ferret, skunk, raccoon, fox, or bat—go see your doctor right away. You may need to start the rabies vaccine series as soon as possible, before symptoms of the illness appear.

CDC Resources

Vaccines and Preventable Diseases: Rabies Vaccination

How can you prevent rabies in people?

Rabies: When should I seek medical attention?


CDC Publications

Parents’ Guide to Childhood Immunizations, 2010

Rabies Vaccine: What You Need To Know

Publications: Parents’ Guide to Childhood Immunizations

Page last reviewed: May 8, 2018