Are Vaccinations Safe?

Written by Amy Boulanger | Published on November 6, 2014
Medically Reviewed by Brenda B. Spriggs, MD, MPH, MBA on November 6, 2014

Vaccine Safety

Vaccines are rigorously tested for safety. An overwhelming amount of research has shown that vaccination is safe and effective. That doesn’t mean that vaccination can’t cause side effects. Like all drugs and medications, vaccines do have some risks. These risks are generally mild.

Factors that increase your risk of a side effect include:

  • being sick at the time of vaccination
  • having a family history of vaccine reactions
  • immune suppression

Serious negative reactions to vaccines are rare. For most people, the risk of getting a disease is much higher than that of an adverse reaction to a vaccination.

Questions to Consider

Like medication, everyone responds differently to vaccines. Different types of vaccines each carry their own set of side effects. These can range from mild to more serious reactions. However, lasting consequences are rare.

If you’re concerned about vaccination, here are some questions to consider:

  • Can you schedule the vaccine for a time when you’re not sick?
  • Have you ever had a vaccine reaction?
  • Do you have a family history of vaccine reactions, allergies, or immune disorders?
  • Are you fully aware of vaccine side effects?
  • Do you understand how to recognize a reaction to a vaccine?
  • Are you allergic to eggs, shellfish, or other potential vaccine components?

In addition, some people may not have an effective immune response. Such individuals remain susceptible to infection after vaccination.

Adverse Events

The United States tracks adverse events using the Vaccine Adverse Events Reporting System (VAERS). This allows them to determine if a vaccine has problems with safety. VAERS researchers investigate serious adverse event reports to see if they are actually related to a vaccine. They also track the frequency of minor adverse events.

It’s important to remember that not all health problems that occur after a vaccine are caused by the vaccine. Sometimes people just get sick. That’s why formal investigation and tracking is critical.

You should write down any health problems you have after a vaccination. Then, contact your doctor to let them know about any potentially adverse events. Possible symptoms of an adverse vaccine reaction include:

  • swelling, redness, or heat near the injection site
  • rash or hives
  • muscle weakness
  • joint pain
  • high fever
  • extreme fatigue
  • sleep disturbances
  • memory loss
  • weakness or paralysis in any area of the body
  • vision or hearing loss
  • restlessness or hyperactivity

Safety, Fraud, and Controversy

Vaccines have been enormously successful in controlling and eliminating deadly diseases. They are also heavily tested and quite safe. That doesn’t mean they have avoided controversy.

A fraudulent study published in the late 1990s kicked off several decades of anti-vaccine rhetoric. The study claimed to link vaccination to autism. However, the data was later shown to be falsified. Unfortunately, even a retraction didn’t stop some people from speaking out against vaccines. 

The truth is that serious vaccine side effects are rare. Individual adverse events are tragic. However, widespread vaccination helps far more people than it harms. It not only protects individuals, it also protects the communities in which they live. As more people are vaccinated, the likelihood that someone susceptible will come into contact with a disease goes down. This form of protection is known as herd immunity.

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Show Sources

  • Flaherty, D. K. (2011, October). The vaccine-autism connection: a public health crisis caused by unethical medical practices and fraudulent science. Annals of Pharmacotherapy, 45(10), 1302-1304.
  • Frequently asked questions about vaccine safety. (2011, February 8). Retrieved from
  • Vaccine adverse events reporting system. (n.d.). Retrieved from
  • Wakefield, A. J., Murch, S. H., Anthony, A., Linnell, J., Casson, D. M., Malik, M., … & Smith, J. A. (1998). Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. The Lancet, 351(9103), 637-641. Retraction in: The Lancet, 375(9713), 445. (2010, February 6).
  • Why immunize? (2014, September 23). Retrieved from
  • Why it’s important to monitor vaccine safety. (2013, September 25). Retrieved from

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