Vaccines are medications that stimulate your immune system into producing antibodies against specific germs.

There are different types of vaccines, which trick your body into thinking it was infected with this germ before.

The vaccines most people are familiar with are made with weakened or dead organisms of a particular virus. These organisms can’t make you sick, but they imitate the viral infection, causing your body to think it’s developed the illness. Your immune system responds to the vaccine by producing t-lymphocytes (also called t-cells) and antibodies. The t-cells circulate in your blood system looking for abnormalities or infections. The t-cells then “recruit” the antibody-producing lymphocytes and plasma cells.

Once your immune system detects the organism, it makes antibodies to destroy the “invaders.” This leaves your body with a memory of how to fight off that particular illness should you encounter it again. These vaccines are available by injection, by mouth, or by nasal spray, depending on the vaccine.

Inactivated vaccines

Inactivated vaccines are those made with dead germs. The most commonly given vaccines using an inactivated microbe are for preventing:

• Hepatitis A
• Influenza (injection only, not the nasal formulation)
• Polio (injection only, not the oral formulation)

Live-attenuated vaccines

More vaccines are made with weakened forms of the microbes. Attenuated means weakened. The most commonly used live attenuated vaccines include:

• MMR (for measles, mumps, and rubella)
• Rotavirus
• Smallpox
• Chickenpox
• Yellow fever

mRNA vaccines

mRNA vaccines, also called messenger RNA vaccines, entered the public vocabulary as the COVID-19 pandemic raged on. mRNA technology is not new though. Researchers had been working for decades to find vaccines and treatments using mRNA technology, but up to now hadn’t found a good, effective use for it.

Unlike traditional vaccines, mRNA vaccines don’t have any virus form in them. Instead, the vaccine uses genetically engineered mRNA to instruct the body how to produce copies of a protein found on the outside of the virus. Once it’s done its job, the mRNA breaks down. It doesn’t enter the DNA, nor does it alter DNA in the body. It also doesn’t prevent someone from contracting the infection. Instead, the vaccines reduce the risk of severe illness and death.

Conjugate vaccines

Other vaccines, called subunit, polysaccharide, recombinant, and conjugate vaccines are made with parts of microbes, depending on the infection. The most common ones include vaccines against:

• Shingles (herpes zoster)
• Whooping cough
• Hepatitis B
• Hib (Haemophilus influenza type b) disease
• Pneumococcal disease
• Meningococcal disease

Toxoid vaccines

Toxoid vaccines are what the name implies: they contain a toxin or chemical made by bacteria or a virus. The vaccines provide immunity to the harmful effects of the infection, instead of to the infection itself. Vaccines for tetanus and diphtheria are toxoid vaccines.

Viral vector vaccines

The Johnson & Johnson COVID-19 vaccine, which is no longer available in the U.S., used viral vector technology. This technology has been around for a few decades, like mRNA. It involves using a modified version of a separate but similar virus to send messages to the body about how to fight the infection. With the COVID-19 vaccine, the virus vector was an adenovirus, one of the viruses that cause the common cold.

Vaccines take time to work

It can take anywhere from several days to a few weeks for a vaccination to become effective. For example, if you receive chickenpox vaccine and you spend time with someone who has the disease within a few days of the injection, you may still become ill. When this happens, some people believe that the vaccination made them sick, but this isn’t so. They were exposed to the virus before their immune system had a chance to react to the vaccine.

Why vaccinations instead of natural immunity?

When you contract a virus, such as a meningitis or measles virus, your body tries to fight it. If it’s successful and the illness goes away, you usually develop an immunity to the disease and you shouldn’t get it again. Or if you do get the illness, it may be milder than it would have been ordinarily. This is a natural immunity. However, these illnesses are serious and can cause long-lasting damage to your body, and even sepsis and death. Vaccinations significantly reduce the damage many common viruses and some bacteria can cause. For example, in the early 1900s, an average of 503,282 people died of measles each year in the U.S. Because of vaccinations against the illness, in 1990, only 89 people in the U.S. died from measles.

Keeping vaccines up to date

You may recall you or your child getting some vaccines in a series. These vaccines need more than one dose for your immune system to recognize and build up antibodies against some viruses. Other vaccines need a booster shot years later because immunity wears off. Therefore, it’s important to follow vaccine and booster schedules, even for adults. The newest shingles vaccine requires two injections within two to six months of each other.

Recommended vaccines

The Centers for Disease Control (CDC) maintains a recommended vaccine schedule for children and teens. Following the recommended schedules gives your children the best chances at reducing their risk of developing these largely preventable illnesses and associated complications that could occur.

Adults who haven’t received the recommended vaccines as children can still receive vaccinations against the diseases. Other recommended vaccines include those that prevent pneumonia, shingles, influenza, and COVID-19.

Extra vaccinations

If you travel to other countries or work in a field that could expose you to certain illnesses, you may be required to receive additional vaccines. Before your travels, check with the CDC and your doctor to see which vaccines are recommended and which are mandatory. It takes several weeks for some vaccines to be fully effective, so leave yourself enough time before your departure date. Some countries will deny entry to people who have not received mandatory vaccinations, particularly if you are going to specific locations, such as the jungle or farmlands.

Exceptions to vaccinations

Not everyone can receive vaccines. People with a weakened immune system might have to delay or not receive vaccinations at all. Some are allergic to an ingredient in a particular vaccine. The people around them can provide herd immunity through their own vaccinations.  If the people who are regularly in contact with the unvaccinated person are vaccinated, the unvaccinated person has a lower chance of being exposed to the virus or bacteria and becoming ill.

If you suspect sepsis, call 9-1-1 or go to a hospital and tell your medical professional, “I AM CONCERNED ABOUT SEPSIS.”