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Adult Vaccines Part I: An Introduction to the Basics About Vaccines

Posted on Friday, September 27, 2019 by UVM Health Network - CVMC

Many adults in the United States are considered immunized against various diseases due to previous exposure to the diseases themselves, or through vaccinations. These vaccinations, for diseases caused by certain bacteria and viruses, are given in order to create immunity against a variety of pathogens that can make us sick. Some of these childhood vaccinations are considered effective for a lifetime, while others will need to periodically be “boosted” at certain intervals throughout adulthood.

Depending on your age, medical history, life circumstances and many other factors, you may need to even get new vaccinations as an adult, healthy or not.

As an example of why we should get vaccinated, there’s this statistic:

It is estimated that upwards of 50,000 – 70,000 adults in the United States (US) die each year due to pneumonia and influenza (also known as “the flu”), many of which could be prevented with appropriate vaccinations.

The purpose of the first part of this two-part series on adult vaccinations is to introduce basic terminology, biological basis, safety, immunizations goals, concepts and standard schedules for a healthy adult. The second part of this series will discuss more in-depth about the specific vaccinations that are recommended.

Vaccination Basics

Vaccinations, also called “vaccines” or “immunizations,” can prevent certain serious or deadly infections. The immune system is what our body uses to protect against illness and infection. When a foreign organism is introduced, such as a bacterium or virus, the immune system responds by creating antibodies, which are proteins. These antibodies help to fight the infection, and also allow the immune system to recognize the foreign organism the next time that a person might be exposed. This typically translates to a person not becoming ill the next time that they are exposed to the organism, and a good example that most adults can relate to is chickenpox, from the Varicella Zoster virus. Many of us had the disease once during our childhood, so we developed antibodies to protect us from getting it again in our lifetimes. In 1995, a vaccine against Varicella was made available, and with use of this vaccination, many young adults and children now do not have to experience the uncomfortable sickness and itchy rash to become immune.

Types of Vaccinations

There are two types of vaccinations: active and passive.

  • Active vaccines are made from weakened forms or parts of the pathogen, and use this to stimulate the immune system to produce antibodies.
  • Passive vaccines use antibodies obtained from a large pool of donors and provide temporary immunity.

Effectiveness of Vaccines

Immunizations are a very effective way of preventing, and sometimes even eradicating, diseases. An example of a successful vaccine program is smallpox, which used to kill millions of people around the world annually, but now has been eliminated due to an intensive vaccination program. Cases of tetanus and diphtheria are now rare in the US and other developed countries due to vaccination, but still remain more common in undeveloped countries.

Many of the pathogens that we vaccinate against are very contagious, meaning that they spread easily to non-vaccinated or under-vaccinated individuals. Preventing these illnesses through immunization is especially important for certain groups of vulnerable people, such as the elderly, young children, people with a lowered immune system and others. Getting and staying up-to-date on vaccinations decrease the chances of getting certain illnesses for individuals, but also work to decrease the likelihood of transmitting the diseases to others, including those vulnerable populations. This strategy is referred to as “herd immunity.”

Risks and Side Effects from Vaccines

In most cases, there are very few risks or side effects from vaccines. If side effects do occur, they are usually mild, and can include:

  • mild fever,
  • reddish/tender area at the injection site, and
  • sometimes a more systemic reaction with flu-like symptoms.

Severe side effects are rare, but can include neurologic reactions or severe allergic reactions such as anaphylaxis. Again, these are rare, and are potential side effects for many of the medications that we prescribe and take routinely for other medical conditions, such as high blood pressure.

There are some contraindications (a specific situation in which a vaccination should not be used because it may be harmful to the person) for certain vaccines, which include:

  • Allergy to eggs, neomycin, streptomycin, gelatin, specific vaccines
  • Having a weakened immune system (mild, acute illnesses do not apply)***
  • Patients with a recent blood transfusion or immune serum globulin
  • Women who are pregnant or are considering becoming pregnant within the next 28 days***

***this applies exclusively to live vaccines

It is important to speak with your medical provider if you have any of these allergies or other contraindications to get vaccines. In some cases, alternative vaccines can be provided, should they be necessary.

Recommended Vaccinations

Most healthy individuals are recommended to get the following vaccines during their lifetime:

  1. Pneumococcal
  2. Influenza
  3. Tetanus, Diphtheria, Pertussis (Tdap)
  4. Measles, Mumps, Rubella (MMR)
  5. Varicella
  6. Herpes Zoster (Shingles)
  7. Hepatitis B
  8. Hepatitis A
  9. Meningococcal
  10. Human Papillomavirus (HPV)

Although the majority of healthy adults will need most, if not all, of these vaccines, certain circumstances may dictate that less or more of them are necessary. It is best to discuss this with your medical practitioner, in order to create a tailored immunization plan that is right for you.

Also, make sure to notify your medical practitioner if any of the following apply to you, as you may need adjustments to a normal vaccination schedule:

  • Residents of long-term care facilities, college dormitories, correctional facilities or household members living with at-risk individuals
  • Healthcare or public safety workers, laboratory staff, daycare center workers, and food handlers
  • International travelers
  • Men who have sex with men, people with multiple sex partners, and those who use injectable street drugs

If you are not sure whether or not you’re immune to certain vaccine-preventable illnesses, you can speak with your health care provider to check your records. If there is no record of certain immunizations, it is possible to check “titers,” which help to determine immunization status through blood testing. With most vaccinations, it is safe to receive a vaccine even if you are immune to the disease(s), through having contracted the disease(s) or via vaccinations. Again, discuss your concerns with your health care provider.

Cost of Vaccines

One final aspect of immunizations that warrants consideration is cost. The federal government and state of Vermont provide certain medical facilities with vaccines, which can be typically given regardless of health insurance status. But, this is not always the case, and health insurance companies can vary on the level of coverage for certain vaccines. Your health care provider can likely give you some advice on whether or not a vaccination will be covered by your insurance, but the most reliable sources for this information are your health insurance carrier or a pharmacist.

Stay tuned for Part 2 of this article, which will discuss the specifics of the recommended vaccinations for healthy adults, including recommended timeline, efficacy, contraindications and more.

DISCLAIMER: As always, these articles are intended for educational purposes, and may not represent the most appropriate recommendations for each individual. It is best to check with your medical provider with any questions or concerns.


  1. Center for Disease Control:
  2. UpToDate:
    “Patient education: Adult vaccines (Beyond the Basics)”
     “Patient education: Vaccines for adults (The Basics)”

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