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From safety to effectiveness, we're here to explain five important things to know before your next vaccination.


Do you remember your first vaccine? Probably not, as many of us received vaccines at a very young age. Vaccines can be incredibly important to the overall health and wellbeing of you, your family, and the greater community. To help you prepare for upcoming vaccines, here are five interesting, helpful facts about them.

1. It Takes a Long Time to Make a Vaccine 

An incredible amount of time, testing, and evaluation goes in to developing, approving, and manufacturing a vaccine for use in the United States.We're talking years and years of facilitating, monitoring, and evaluating clinical trials to ensure that the vaccine is safe for use.

According to the Centers for Disease Control (CDC), highly trained scientists and doctors at the U.S. Food and Drug Administration (FDA) run clinical trials in three separate phases before approving a vaccine for use.2 The first phase looks at the impacts of the vaccine in a small group of 20-100 people to observe safety, effectiveness, dosage, and side effects. The second phase then tests the vaccine in several hundred volunteers. During this phase, researchers consider the most common short-term side effects and study volunteers' immune reaction to the vaccine. In the third and final phase, researchers evaluate the vaccine in hundreds or even thousands of volunteers. With this many volunteers, researchers are able to consider how people who receive the vaccine compare with those who do not receive the vaccine.

A hand injecting a sample into a vial with a needle

Even after a vaccine has been through clinical trials, it still needs to be evaluated by another group of medical experts in order to be added to the U.S. Recommended Immunization Schedule. This group is called the Advisory Committee on Immunization Practices (ACIP) and is made up of medical and public health experts, as well as members of the American Academy of Pediatrics (AAP) and American Academy of Family Physicians (AAFP).

Together, committee members review the clinical trials in great detail, once again considering safety, effectiveness, and severity of the disease that the vaccine helps prevent, and how many people could be impacted by the disease if the vaccine is not approved. The group takes special care to review how the vaccine reacts in different age groups, particularly young children. Once ACIP makes their recommendation and the CDC Director signs off, the vaccine will be added to the U.S. Recommended Immunization Schedule.

MedExpress Pro Tip: For new parents, keeping up with vaccinations for your children can be overwhelming. The CDC has great resources to help parents keep track of previous immunizations at every age. For more information, visit

2. Herd Immunity

According to the CDC, vaccines have the potential to help prevent the hospitalizations of tens of thousands of people every year.1 Some serious illnesses, such as measles, mumps, rubella, pertussis, and influenza, may be prevented by getting vaccinated (sometimes you'll even get a lollipop afterward!).

Have you ever heard of herd immunity? Otherwise known as community immunity, herd immunity is a form of immunity that occurs when a large portion of a population is vaccinated. The vaccinated population then has the ability to provide a level of protection to those who aren't able to get vaccinated, like those with serious allergies or weakened immune systems. This slows the spread of germs and makes it less likely for entire communities to become sick and can help prevent disease outbreaks. Sometimes, herd immunity can even make certain diseases extremely rare or completely wipe them out.


MedExpress Pro Tip: Phone a friend! If the sight of needles stops you from getting vaccinated, ask a friend or family member to come along with you. Maybe you’ll inspire your vaccination buddy to check that he or she is up to date on vaccinations as well!

3. Decreased Diseases

Since the introduction of vaccines, infections and diseases like polio, smallpox, and diphtheria have become increasingly rare worldwide. Cases of other diseases have also gone down significantly. Measles cases, for example, have gone down from an estimated average of 503,282 annual cases in the 20th century to only 71 cases in 2009.3

4. A Variety of Vaccines

Different vaccines may be recommended for travel, work, or school. At MedExpress, we offer a variety of vaccines, including:

  • Td (tetanus and diphtheria)

While rare in the United States today, tetanus and diphtheria are both serious diseases. Those who become infected may experience severe complications, including lock jaw in patients with tetanus and damage to the heart in patients with diphtheria.

The Td vaccine, however, can help protect adolescents and adults from these diseases. Typically, Td is given as a booster every 10 years, but a healthcare professional may recommend it sooner if you have been exposed to someone with diphtheria, which is spread through coughing or sneezing. Professionals may also recommend an earlier vaccination to help protect you from tetanus after certain types of wounds.

  • Tdap (tetanus, diphtheria, acelluar pertussis/whooping cough vaccine)

Tdap vaccine is very similar to Td vaccine, but in addition to preventing against tetanus and diphtheria, Tdap also helps prevent against pertussis, which is more commonly known as whooping cough. Whooping cough causes severe coughing, which can result in vomiting, trouble breathing, and difficulty sleeping.

Children typically receive one dose of Tdap around age 11 or 12. For any adult older than 19 who has not been previously immunized for Tdap, the CDC recommends a single dose of the Tdap vaccine. Like Td, a Tdap booster is recommended every 10 years or earlier as needed.

  • Flu vaccine

The CDC recommends that everyone six months or older receive an annual flu vaccine prior to the start of flu season, which may begin as early as late summer or early fall. Flu is a very serious disease that impacts millions of people in the United States each year and can lead to severe complications and hospitalization. The benefits of getting vaccinated against the flu may include helping slow the spread of germs in a community (hey, herd immunity!) and may help prevent those with chronic conditions like asthma and diabetes from experiencing severe complications as a result of the flu.

A doctor disinfects a patient's skin before administering a vaccination

  • MMR (measles, mumps, rubella)

Getting an MMR vaccine is an important first step to help prevent against measles, mumps, and rubella. These are viral diseases that can be especially serious in children. Measles, mumps, and rubella are often preventable with two doses of the MMR vaccine. The first dose can be given at 12 through 15 months old and the second dose at 4 through 6 years old. If you have never gotten an MMR vaccine and would like to receive one, talk to a healthcare professional about when it makes sense to get vaccinated.

The MMR vaccine is only offered in select MedExpress centers. Please call your local center for more information.

  • Hepatitis B

Hepatitis B, a serious infection that causes inflammation of the liver, is one of the most common hepatitis viruses in the United States. Infants typically receive the vaccination early on; however, children and adults who have not previously completed the hepatitis B series may also get vaccinated to prevent against hepatitis B. The vaccine is usually given as a three- or four-shot series over a six-month period.

  • Hepatitis A

Hepatitis A is also a serious disease that causes fever, fatigue, stomach pains, joint paints, and jaundice - or yellowing of the skin or eyes. To prevent against Hepatitis A, a person receives two doses of the hepatitis A vaccine, given at least 6 months apart. Children are typically vaccinated between their first and second birthdays. Persons traveling to countries where Hepatitis A is common may also get vaccinated before their trip.

5. Vaccines are Easy

Whether you're traveling out of the country or headed to your freshman year at college, MedExpress makes it easy to keep your vaccinations up to date. MedExpress offers convenient weekend and evening hours, so you can schedule an appointment or just walk in at a time that fits your schedule.



1 CDC: For Educating Your Adult Patients. Last updated January 26, 2018. Accessed March 30, 2023.

2 CDC: How Vaccines are Developed and Approved for Use. Last updated March 30, 2023. Accessed September 14, 2023.

3 NIAID: Vaccine Benefits: The Impact of Vaccines in the United States. Last updated March 6, 2014. Accessed August 8, 2018.

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