How Vaccines Work

vaccination of children. An injection. Selective focus; blog: How Vaccines Work

August is National Immunization Awareness Month (NAIM), so it’s the ideal time to learn some more about how vaccines work and why they are so important. According to the World Health Organization (WHO), immunization currently prevents 2-3 million deaths globally each year. However, another 1.5 million deaths could be avoided if more people were vaccinated.

About the Immune System

To understand how vaccines work, you have to know a little bit about the human immune system. When bacteria or viruses get into your body, they begin attacking your cells and multiplying. This is what causes the infection that makes you sick. Your immune system is responsible for fighting off these germs using white blood cells.

There are different types of white blood cells with different functions. Macrophages are responsible for absorbing and breaking down pathogens (germs). This process leaves behind the part of the germ called the antigen.  Lymphocytes attack antigens and create antibodies. Once the infection has been cleared, the body keeps the antibodies that will help prevent the same pathogens from making you sick again. This is called building immunity.

How Vaccines Work With the Immune System

Vaccines help the body build immunity by imitating an infection to prepare your body for the real thing. The “infections” vaccines imitate don’t make you sick, but they cause the body to develop the white blood cells and antibodies needed to protect against an actual infection. It takes a couple of weeks to build immunity after vaccination.

Types of Vaccines

There are several different types of vaccines. The type of vaccine needed to protect against illness depends on what kind of infection it is (viral or bacterial) and how the germ cells behave. The five main vaccine types used today are:

  • Live, attenuated vaccines: Fight viruses and bacteria with a version of the living virus or bacteria that has been weakened so it doesn’t cause sickness.
  • Inactivated vaccines: Contain inactive forms of pathogens. Dead germ cells can still trigger the body to develop a defense against the antigens. Inactivated vaccines often require multiple “booster” doses.
  • Toxoid vaccines: Prevent diseases caused by bacteria that produce toxins in the body. The vaccines contain weakened versions of the toxins that don’t cause illness.
  • Subunit vaccines: Contain only a part of the virus or bacteria (called subunits) instead of the whole germ. 
  • Conjugate vaccines: Fight bacteria that have an outer coating of sugar-like materials called polysaccharides. The coating of the germ hides its antigen so the immune system does not recognize it. The vaccine connects the polysaccharides to antigens that the body has immunity to. Conjugate vaccines teach the body to have an immune response to the coating as well as the antigen it hides.

Vaccines & Herd Immunity

If you pay attention to the conversations surrounding how vaccines work, you’ve probably heard the term “herd immunity” or “community immunity” used. Vaccines don’t just protect people on an individual basis, they can also protect entire communities and populations.

How Herd Immunity Works

Herd immunity occurs when most of the people in a population have been immunized against disease. When most of the people in a group are immune to an illness, the chances of it being transmitted to others and causing an outbreak are very low. That protects everyone in a community, including those who are unable to get vaccinated. Herd immunity is the key to how many diseases that used to devastate populations have been eliminated even when every person is not vaccinated.

Why We Need Herd Immunity

Herd immunity is important because there will always be a certain number of people who can’t safely get vaccinated for medical reasons. For instance, very young babies, the elderly, people with severe allergies, pregnant women, and people with compromised immune systems cannot always get vaccinated for certain things.

Herd immunity does not work unless the people who can get vaccinated do get vaccinated. If too many people choose not to get vaccinated, then there are more places for a virus or bacterium to land and cause infections. This can lead to an outbreak that threatens those who were unable to be immunized for legitimate medical reasons.

Make an Appointment

The board-certified pediatricians and staff at Wake Forest Pediatrics are dedicated to providing quality care to patients in Wake Forest and Knightdale. Our comprehensive approach focuses on teamwork and open communication with patients and parents. If you have questions about immunizations for your child, call our Wake Forest office at 919-556-4779 or our Knightdale office at 919-266-5059 to make an appointment.

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