Vaccinations and Immunizations


It’s easy to forget that, like children, adults need protection against life-threatening diseases too. Adults need different vaccines based on their health, age, lifestyle and occupation, while children need vaccines based on age alone.

It’s more complicated to determine what vaccines adults need. One size does not fit all. But the good news is Mercy can help you determine which immunizations are right for you.

How Vaccines Work

Vaccines work with our bodies to fight disease. When germs, such as bacteria or viruses, invade the body, they attack and multiply, leading to an infection or illness. Our immune system is designed to fight infections. Vaccines help us develop immunity by imitating an infection. Vaccines almost never cause illness, but they cause the immune system to produce infection-fighting cells and antibodies.

However, it typically takes a few weeks to produce these disease-fighting cells after vaccination. The most common side effects, like low-grade fever and fatigue, are mild. However, many vaccine-preventable disease symptoms can be serious or even deadly.

Why Do We Need Vaccines?

Some people believe that naturally acquired immunity — immunity from having the disease itself — is better than the immunity provided by vaccines. 

However, natural infections can cause severe complications and be deadly. This is true even for diseases that many people consider mild, like chickenpox. It is impossible to predict who will get serious infections that may lead to hospitalization. Although many of these diseases are rare in this country, they circulate around the world and can be brought into the U.S., putting unvaccinated members of the community at risk.

Vaccine Schedules

It's not your fault if you don't have all the immunizations (vaccinations) you need. Recommendations change over time, so it’s important to regularly monitor your vaccination needs.

View an adult immunization schedule

Vaccine Safety

Vaccines, like any medication, can cause side effects. Sometimes, after getting a vaccine, you may have minor symptoms, such as fever. These symptoms are normal and once the imitation infection goes away, the body is left with a supply of “memory” cells that fight that disease in the future. Your Mercy provider will talk about any safety concerns you have and can tailor a vaccination schedule to your individual needs.

Here are some common pre-vaccination safety questions your doctor may ask:

  • Are you allergic to eggs?
  • Do you have a history of Guillain-Barre syndrome?
  • Have you ever had a severe allergic reaction to a vaccine?
  • Do you suffer from seizures?
  • Are you allergic to latex?
  • Do you currently have a weakened immune system?
  • Do you suffer from a bleeding or blood clotting disorder?
  • Are you currently pregnant or breastfeeding?  

The most commonly administered vaccine is used to fight influenza (flu). The flu vaccine changes annually to keep pace with the viruses most likely to spread, so adults and children (6 months and older) need a dose every year.

Measles, mumps and whooping cough may seem like old-fashioned diseases, but they have not gone away, and diseases like measles are even making a comeback. These diseases wouldn't spread as quickly ― or be as serious ― if everyone was immunized against them.

Some vaccines like human papillomavirus (HPV) are given as a series of shots over time, rather than a single dose. Not getting a full course of a vaccine leaves a person with limited protection and still at some risk for getting a disease. Other vaccines like Td (tetanus and diphtheria) require periodic booster shots to ensure that immunity remains high.

COVID-19 Vaccine

Get answers to the most frequently asked questions about the COVID-19 vaccine, learn more. 

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