Why do we need vaccines?

By Gloria M. Rivera

August is National Immunization Awareness Month and given the times we live in, vaccines are quite “in”. That’s why I decided to write a bit about what vaccines are, how they work, and why they are useful. 

COVID-19 is an infectious disease caused by a virus. As such, it cannot be treated with an antibiotic. Also, since it is relatively new, there is no cure available to date. The best way to deal with it is through prevention. This is done by washing our hands, wearing a mask, practicing social distancing, and getting vaccinated. 

When you read about getting vaccinated, getting the shot (in EN-US), or getting the jab (in EN-UK) you may have also seen terms as immunization, vaccination, and inoculation. These terms are usually used interchangeably,  in spite of having different meanings. Therefore,  using them correctly can help prevent misunderstandings.

Jab COVID vaccine
Shot COVID vaccine

What’s the difference?

According to the World Health Organization (WHO), these are the correct definitions:

  • Vaccination uses vaccines to stimulate the body’s own immune system to protect a person against future infection or disease.
  • Immunization is the process where a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine.
  • Inoculation, meanwhile, is often used interchangeably with vaccination or immunization. This term describes the introduction of a substance into the body to provide protection. The term was first coined in the 18th century to describe variolation, the use of a small amount of pus from someone with smallpox into the body of someone without it.

How vaccines work:

A pathogen is a bacteria, virus, parasite, or fungus that can attack us. Our body has many ways of defending itself against these microorganisms. It has physical barriers, such as skin, mucus, and cilia, that prevent them from getting in. But when they do, our immune system is there to protect us. 

Our immune system recognizes a part of a pathogen as a foreign substance or antigen. Then, it produces antibodies against this antigen, attacks it, and eliminates it. These antibodies are specific because they only attack this antigen. We have thousands of different antibodies in our bodies and that protects us against many diseases.

When our body produces antibodies against a pathogen, it also creates memory cells. These cells “remember” this microorganism so when our body is exposed to it again, the reaction is much faster and more effective than the first time. This response is specific and provides long term protection.

Getting vaccinated works the same way as when we are exposed to a disease. The difference is that these antigens do not cause the disease, but our immune system still creates antibodies as if we were exposed to the pathogen. This way, when we encounter the microorganism for the first time, we are ready to attack it in a more efficient way.

For example, when we are around a year old we get the varicella or chicken pox vaccine. Then, our immune system produces antibodies against this virus. If we are exposed to this pathogen, we get chicken pox, but it is a much milder version than if we had gotten it without being vaccinated.

Why most of us should get vaccinated:

There are people who cannot get vaccinated and are more likely to catch a preventable disease. For example, people who have had a severe allergic reaction to one of the components of a vaccine (i.e. Polyethylene Glycol (PEG) or Polysorbate are components of mRNA vaccines) or people who are immunosuppressed because they have a weakened immune system (i.e. medications or chronic illness).

When enough people in a community are vaccinated it reduces the number of people able to spread the infection within that community. This is how we have been able to eliminate (or nearly eliminate) diseases like polio, mumps, whooping cough, tetanus, and measles, which once killed millions of people.

That is why it is so important for the people who can get vaccinated to do so. This protects everyone, even those who have not been vaccinated yet or who cannot get vaccinated. This process is called herd immunity.

When enough people in a community are vaccinated, it can provide protection to everyone, even those who have not been vaccinated. It does so by reducing the number of people able to spread the infection within that community, a process referred to as herd immunity.

Why do we need to get so many vaccines?

We get vaccinated since birth through adulthood based on the general risk of us catching a certain disease. This risk depends on our age, health condition, or other risk factors as explained below: 

  • Children follow a recommended schedule to get protection against specific diseases when they are most vulnerable to them. Every country has a different vaccination schedule based on the most common diseases kids will be exposed to. You can find the vaccination schedule of US, Peru, and Japan below.
  • Adults also need vaccines. There are 3 vaccines recommended for all adults by the CDC: influenza, Tdap or Td, and COVID-19. Also, there are five others that are recommended if one has not been adequately vaccinated or has certain health conditions such as HPV, MMR, varicella or chickenpox, pneumococcal disease, and herpes zoster or shingles.
  • Travelers need extra vaccines that different from the ones administered in the routine vaccination schedule. Most of them need to be administered ahead of time to give you full protection against a disease. The CDC has different recommendations for every country. For example, if you want to travel to Peru, the CDC recommends that you to be up to date with routine vaccinations (varicella, diphtheria-tetanus-pertussis, influenza, measles-mumps-rubella, and polio), COVID-19, hepatitis A, hepatitis B, rabies, and yellow fever. 

I hope this short blog post helped you understand vaccines better, how they work, and why they are so important to all of us.

For more information and resources, feel free to check the resource section below.


CDC Vaccine Schedule
US Immunization Schedule
Peru Immunization Schedule
Peru Immunization Schedule
Japan Immunization Schedule
Japan Immunization Schedule