Vaccine Basics

West End Healthline
by Lily Thompson, MD

With the school year in full swing and the Saint Paul Public Schools preparing for a possible transition to hybrid learning on November 16, many children will be offered vaccines during visits to the doctor. Some may wonder how these shots work, protecting us from dangerous diseases.

Vaccines work by using our body’s natural immune systems to fake an infection, spurring our bodies to prepare an immune response for dangerous infections before we are faced with them. Our bodies recognize what they think is an attack and develop antibodies to protect against that attack. These antibodies, made through random trial and error, work much like a lock and a key, each formed into exactly the right shape to stop a particular virus.

A virus that mutates quickly, creates additional challenges—namely that any effective vaccine will not work for long. This is why there is no vaccine for HIV and there is a new flu vaccine every year.

There two types of vaccines: live-attenuated and dead. Live-attenuated vaccines have weakened forms of a virus, while dead vaccines are made of small pieces of a virus or bacteria and have no ability to copy themselves. Live vaccines are more effective at creating immunity to a disease because the damaged virus is still similar to the original. Live vaccines — commonly used with illnesses such as Measles, Mumps, Rubella, and Varicella — generally cause a stronger and long-lasting immune response, however, and there is the very small chance that a live vaccine could change back from its weak form into a form that could cause disease. That is why people with weakened immune systems or pregnant women should not get live vaccines. Dead vaccines including flu and tetanus carry no such risk, but because our immune system is less likely to think that a small piece of virus is a threat, they are often less effective than live vaccines. This is why you need to get booster shots of certain vaccines.

Herd immunity is an important concept we when are talking about vaccines. Herd immunity is the amount of people who need immunity to a disease to prevent it from spreading through a community. It provides an indirect form of protection for children who cannot get vaccinated due to medical reasons.

Every virus has a different percentage required to reach herd immunity. It depends on have infectious, or how easy to spread the disease that virus is. For example, measles is very infectious. The measles virus can live for up to two hours in an airspace where the infected person has coughed or sneezed. Since it is so easy to spread, we need 93-95 percent of population to be vaccinated against measles to prevent community spread. So, it becomes very important for anyone who can get the vaccine, to get it. A large portion of that 5 percent is taken up by children under 1, who cannot get the vaccine yet, and those with weakened immune systems.

Some people believe that immunity from having the disease is better than immunity from a vaccine. However, natural infections can cause severe complications and be deadly. This is true even for diseases that many people consider mild, like chickenpox. We often cannot predict who will get serious infections. And even with how great modern medicine is, the diseases that vaccines prevent can still prove very serious. Vaccines have even wiped out an entire disease, smallpox. They have saved millions of lives. According to a recent study, they prevent nearly 20 million cases of diseases, including over 40,000 deaths, for every generation of Americans. Vaccines are one of the most important advances in healthcare.

As the COVID-19 pandemic continues to surge throughout Minnesota as well as the rest of the country, many are hopeful that vaccines in development — some of them live-attenuated and others dead — will someday soon allow us to beat the disease. With experts predicting that herd immunity will require at least 50 percent of the population to have antibodies, it is important that patients understand the science and benefits such a vaccine will offer.