When you get sick, your body fights off the illness through your immune system. In the process of fighting off the disease or illness, the immune system develops antibodies, which are Y-shaped proteins specific to that virus, bacteria, or other pathogen that will help you fight off the disease the next time it enters your body. In many cases, the antibodies will prevent you from getting sick again. We call this “immunity.”
Immunization can happen naturally, as described above, or it can occur through inoculation by a vaccine. There are different types of vaccines that work somewhat differently, but the goal of every vaccine is to stimulate your immune system to recognize a pathogen and develop antibodies against it.
Some illnesses create complete immunity in the body – you only catch it once. Others, such as the flu, can be caught repeatedly because they mutate. While you may have immunity to one particular strain, you could catch another strain of the flu. But your body will have developed some antibodies that should lessen the severity of a future bout of the flu.
The same is true for vaccines. Many vaccines, especially those against childhood disease, give complete immunity. Others may require booster shots to maintain immunity or to provide protection against additional strains of the illness. This is why detailed immunization schedules have been developed by the CDC for both children and adults, to guide doctors and patients in determining what vaccines may be advisable.
Types of vaccines
Most people are familiar with the concept of “live” and “inactivated” vaccines because these are the oldest forms of vaccine. The first vaccines were inactive vaccines, casually referred to as “dead” vaccines. The virus or bacterium is grown in a lab and then treated with heat or chemicals to inactivate it before putting it in a vaccine. These vaccines cause few side effects but may provide less robust immunity and may require boosters, such as the polio vaccine.
Live attenuated vaccines involve growing the pathogen in a lab, then selecting the weakest strain and growing another culture from it, repeating this process until a very weak live pathogen is produced. This provides a much stronger immunity, though it can cause more side effects, and those with compromised immune systems should talk to their doctor before taking them. These vaccines include MMR, chickenpox, and rotavirus vaccines.
More recent forms of vaccines include subunit vaccines, such as whooping cough, shingles, hepatitis B, meningitis, and HPV vaccines. These use a portion of the germ rather than the entire germ to stimulate an immune response. The mRNA vaccine, such as the two-dose COVID vaccine, introduces an agent that mimics a portion of the pathogen (but is not a natural part of the pathogen) to stimulate an immune response.
Vaccine safety
According to the U.S. Department of Health and Human Services (HHS), vaccines go through testing and evaluation before being licensed by the Food and Drug Administration (FDA) and recommended for use by the Centers for Disease Control and Prevention (CDC). Once released for use, safety is tracked through the Vaccine Adverse Event Reporting System (VAERS). While serious side effects from vaccines are rare, it is still critical to follow up when such events are reported, in order to determine if they are in any way associated with the vaccine. This information can help the FDA and CDC make any necessary dosage changes or take other precautions.
At BCHIP, our goal is to ensure that every resident of Bucks County has access to quality medical care, including vaccination. Visit our Bucks County Immunization Coalition page for vaccine resources and information about our at-home vaccines for the homebound.
