7 Questions on Vaccines against Diseases

Vaccines prepare the body to defend itself when microorganisms, such as viruses or bacteria, attack it. They contain a very small, safe amount of viruses or bacteria that have been weakened or destroyed.
7 Questions on Vaccines against Diseases

Last update: 18 February, 2021

Vaccines against diseases are given to provide immunity and prevent serious and life-threatening illnesses in both children and adults. They’re very important for the health care of the entire community, especially in the child population.

Vaccines prepare the body to defend itself against microorganisms, such as viruses or bacteria, that may attack the body. They contain a very small and safe amount of viruses or bacteria that have been weakened or destroyed.

This way, the immune system learns to recognize and attack infection if it’s exposed to it throughout life. As a result, you won’t get sick or the infection will be milder.

1. What types of vaccines against diseases are there?

A child getting vaccinated.

Currently, four types of vaccines are available:

  • Live virus vaccines: they use the weakened or attenuated form of the virus. Some vaccines of this type are those that protect against diseases such as measles, mumps and rubella (MMR vaccine) or chickenpox.
  • Inactivated: these are made from a protein or other small fragments taken from a virus or bacteria. One such vaccine is pertussis vaccine.
  • Toxoid vaccines: these vaccines contain a toxin produced by the bacteria or virus. What is obtained with this type of vaccine is immunity to that infection. This includes diphtheria and tetanus vaccines.
  • Biosynthetic: they contain artificial substances that are very similar to some parts of viruses or bacteria. A biosynthetic vaccine is the hepatitis B vaccine.

2. Do vaccinations have side effects?

Vaccines can have reactions or side effects. Depending on the vaccine, these may be fever, a rash or soreness at the area of the injection. Slight discomfort is normal and shouldn’t be cause for alarm.

However, some people may also experience serious side effects, including severe allergic reactions. Although some possible side effects are serious, they’re extremely rare. It’s important to remember that the decision to not get vaccinated also carries very serious risks.

Health care providers conduct vaccination campaigns to protect against infectious diseases that can be deadly. Avoiding vaccination increases the risk of contracting these diseases and spreading them to others.

3. Are some vaccines not 100% effective?

Vaccines are designed to generate an immune response that’ll protect the vaccinated person from future exposure to the disease.

However, people’s immune systems are different and, in some cases, won’t generate an adequate response. Therefore, in such cases, the vaccine won’t effectively protect the patient even after vaccination.

4. Is natural immunity better than immunity acquired by vaccination?

A man getting a shot.

In some cases, natural immunity lasts longer than vaccine immunity. However, the risks of natural infection outweigh the risks involved in the recommended vaccines.

5. Why do some vaccines require boosters?

Some vaccines provide long-term immunity with only one dose, while others require boosters to maintain immunity. Boosters serve as a ‘reminder’ to the immune system.

Recent research has suggested that the persistence of immunity against a particular disease may depend on the typical speed of disease progression in the body.

6. Do we need a new flu vaccine every year?

Unlike most vaccines, which contain the most common strains of a pathogen and rarely change, the seasonal influenza vaccine changes every year. This is because circulating strains of influenza viruses are continually changing.

Every year, researchers choose the viruses that are most likely to circulate over the course of the next influenza season. Based on these, the annual vaccine is made to protect against that year’s most dominant strains.

7. Is it possible to eradicate diseases if there’s a vaccine?

A doctor with a vaccine.

In theory, almost any infectious disease for which an effective vaccine exists should be eradicable. When public health organizations achieve an adequate level of vaccination and coordinated action, we can prevent a disease from gaining strength.

Thus, over time, if there’s no one to infect, the disease should disappear.


You shouldn’t forget that the benefits of immunity acquired by vaccination considerably outweigh the serious risks of natural infection. It’s important to follow the vaccination schedules in your place of residence and keep them up to date.

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  • Posfay-Barbe, K. M., & Greenberg, D. P. (2007). Vacunación. In Atlas de Alergia e Inmunología Clínica. https://doi.org/10.1016/b978-848174943-4.50023-5

  • Ministerio de Salud y Protección Social. (2016). Esquema nacional de vacunación. Programa Ampliado de Inmunizaciones (PAI).

  • Vacunación en adultos. (2017). Acta Médica Costarricense.