What Is Vaccines

Vaccines save millions of lives each year and are among the most cost-effective health interventions ever developed. The immunization vaccines provide has led to many major public health milestones, including the eradication of smallpox, a 74% reduction in worldwide childhood deaths from measles over the past decade, and the near-eradication of polio.

So what is a vaccine? A vaccine is a biological treatment that provides immunity to a particular disease. Vaccines are given when you’re healthy, to keep you from becoming sick. And what’s more—vaccination doesn’t just protect you; it protects everyone who comes into contact with you, including:

  • Old people
  • Children
  • People with weakened immune systems
  • People who can’t be vaccinated for medical or religious reasons

Vaccines work by exposing your immune system to a disease in a controlled way. For instance, a vaccine might contain a dead virus or bacterium, or one that has been weakened so that your immune system can defeat it easily. When you are vaccinated, your immune system encounters the virus or other disease and defends you against it, as if you were sick. Cells in your immune system known as memory cells can “learn” the virus and how to defeat it. Then, if you come into the contact with the disease later, your immune system is prepared.

Some vaccines protect you from common diseases such as chickenpox or influenza (flu). Others protect against very serious diseases such as tetanus (lockjaw) or rabies. Some protect against serious diseases that have almost been eliminated, such as polio. Vaccination against these rare diseases that used to be common can be especially important, because it can prevent a serious outbreak if someone in your community is exposed.

Many vaccinations are given to young children, and some may need to be renewed regularly in adults. You may also need specific vaccines if you’re planning to travel to certain foreign countries, if you’re pregnant, or if you’re planning to get pregnant.

A partial list of diseases that can be prevented by vaccines includes:

  • Anthrax
  • Chickenpox and shingles
  • Hepatitis B
  • HPV (which can cause both genital warts, and lead to cervical cancer)
  • Influenza
  • Lyme disease
  • Measles and German measles (rubella)
  • Mumps
  • Polio
  • Rabies
  • Smallpox
  • Tetanus (lockjaw)
  • Tuberculosis
  • Typhoid fever
  • Whooping cough (pertussis)
  • Yellow fever

Risk Factors For Vaccines

Unfortunately, many people miss vaccinations. A number of factors can cause people to miss vaccinations for themselves or their children. Reasons for missing vaccinations may vary from year to year, or from one community to another. Poor families may miss vaccinations because they don’t have adequate insurance, while wealthier parents may give into fears about side effects of vaccines. And being busy can happen to anyone.

For instance, a study in 2014 found that major reasons for missing vaccinations in the general population included:

  • Low income
  • Lack of health insurance
  • Low education
  • Large families
  • Single-parent household.

By contrast, a 2014 survey from the Australia-based parenting website MamaMia asked users about their reasons for missing or delaying vaccinations. The top 3 reasons included:

  • A sick child. Doctors may recommend delaying a shot if a child has a fever above 100˚F (38˚C), but many parents might put off a vaccination because a child has a cold, which is not recommended and may put a child at risk.
  • Being too busy. This is understandable in a busy day and age, but remember that a missed vaccination endangers your health, your child’s health, and the health of everyone around you—as well as the health of future generations.
  • Believing it isn’t important. About 1.5% of the mothers in the survey thought that vaccination didn’t matter as long as other parents vaccinated their kids. Of course, the more common this belief becomes, the less effective vaccination programs will be in the general population. Low vaccination rates have led to disease outbreaks in many places around the world, including New York, Texas, California, Japan, Australia, and Sweden. Even within the MamaMia survey, 3 out of 4 parents had been sick at some point with a disease that could have been prevented by a vaccine.

An especially troubling risk factor for not vaccinating is a growing fear that vaccines may overwhelm a child’s immune system or cause harmful side effects In particular, the myth that vaccines may cause autism arose from one doctor’s interpretation of a small study published over 15 years ago. Most doctors involved in the study disagreed with this interpretation, and multiple studies since have found no link, but the myth persists, largely because of people’s fear of raising a child with autism. According to one study, 93% of pediatricians have encountered at least one patient who refuses to vaccinate a child.

Vaccines may cause some side effects, including fever and, rarely, short-term seizures that can be frightening to watch. However, the overwhelming scientific evidence demonstrates that the benefits of vaccination outweigh the risks, both for individuals and for communities.


Even for diseases that are rare or nearly eradicated, the benefits of vaccination substantially outweigh the risks. Failure to vaccinate has been linked to outbreaks of preventable diseases throughout the USA and the world.


Getting your vaccinations and making sure your children are vaccinated on schedule is an essential part of preventive care for almost all Americans. To prevent serious reactions to a vaccine, tell the doctor if you or your child:

  • Have any allergies
  • Have ever had a severe reaction to a vaccine
  • Have a compromised immune system for any reason

Also, stay in the doctor’s office for 15 to 20 minutes after the vaccination, so that your doctor can watch for any unusual effects.

Complementary and Alternative Treatment

Alternative approaches, such as breathing exercises or other relaxation techniques, may help with pain or anxiety during or just before a vaccination.

Alternatives to vaccination, such as naturopathic or herbal treatments designed to boost the immune system, may or may not help you stay healthy overall, but they are no substitute for vaccination. When it comes to preventing serious vaccine-preventable diseases, there is no excuse to risk your health, your children’s health, or the health of future generations on treatments that are not supported by scientific evidence.

When To Contact A Doctor

If you are not up to date on your scheduled vaccinations or your children’s vaccinations, talk with your doctor. If you do not know if you are up to date on all scheduled vaccinations, ask your doctor. You should also talk to your doctor about extra vaccinations you may need if:

  • You are pregnant, or you plan to become pregnant
  • You are planning to travel abroad
  • You are entering college or the military
  • You are 65 or older
  • You have a disease that may put you at risk for infections, such as asthma, heart disease, cancer, or diabetes

Questions For A Doctor

When you go to see your doctor, it’s good to have a list of the questions you’d like to have answered. Take a moment to write down some of the things you want to know. Your questions for your doctor might include some of these:

  • Are my/my child’s vaccinations up to date?
  • What does this vaccine protect against?
  • When is the next scheduled vaccination?
  • Should I be on the watch for side effects like fever? How long will these possible side effects last?
  • What signs should I watch for?
  • What should I do if I notice anything wrong?
  • Is there anything else I should know about vaccinations?

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