What Are Vaccines?

Lesson Plan - Get It!

Audio:

Babies and children are exposed to — and vulnerable to — many different diseases and pathogens as they grow up.

Pathogens are viruses and bacteria that cause disease. Immunizations and vaccines can help prevent the transmission of these infections.

These medications work by helping your body recognize and remember the antigen, or toxin, that the immune system works to destroy because it can cause diseases like diphtheria, measles, mumps, and rubella.

Immunization allows your body to respond to the pathogen faster than a typical immune response. Some vaccines provide long-term immunization, or protection, from a disease, while others must be followed up with additional doses.

Before continuing, if you missed or need to review the previous lesson in this Immune System series, find it under Related Lessons in the right-hand sidebar.

This lesson will focus on three main types of vaccines used today: live, inactive, and subunit.

Live vaccines use a weakened sample of the pathogen or microbe so that it does not cause the disease but provides enough exposure so the immune system can remember it.

Live vaccines usually provide long-term immunization after one or two doses.

Individuals with weak immune systems should not receive live vaccines because there is a greater chance of the live microbe replicating and causing an infection.

These vaccines must also be refrigerated, which makes shipping and distribution to remote areas difficult.

Diseases caused by viruses are easier to prevent with live vaccines because viruses remain stable over time. Bacteria often mutate and change, so using live vaccines would be inefficient.

Examples of common live vaccines include measles, mumps, and chickenpox (pictured below).

Inactive vaccines use dead microbes to produce the medication, so they do not require refrigeration and are easier to distribute. Several doses are needed to reach immunization since these have a lower immune response than live samples.

• Have you ever gotten a booster shot?

That is an inactive vaccine! Tetanus is an excellent example of an inactive vaccine because it prevents an infection due to exposure to the tetanus bacteria.

Finally, subunit vaccines use the antigens from a microbe or pathogen to cause an immune response. This prevents accidental infection from introducing the whole pathogen.

The immune system can identify and remember the antigen associated with the microbe without contacting the invader. An example of a subunit vaccine is Hepatitis B, which protects against viral infection.

These three types of vaccines help prevent many infectious diseases by exposing the human immune system to small samples of viruses, bacteria, and pathogens. Allowing the human body to identify small samples enables the body to effectively fight off future exposure that could lead to disease or death.

It is important to note that there are other forms of vaccinations, such as the mRNA vaccines for COVID-19, but these are not as commonly used.

Scientists and doctors use different vaccines to protect against diseases, based on where the disease originates and logistics such as storage.

While live samples offer higher immunity, they are harder to store and ship. Inactive vaccines are more accessible to distribute but often require multiple doses to reach immunity. Subunit vaccines prevent accidental infection but need much lab work to prepare.

• What have you learned about the types of vaccines used in modern medicine?
• Is there a vaccine you wish we had access to? Why?

In the Got It? section, you will learn more about the controversy surrounding mandatory vaccinations in the United States.