everything you ever wanted to know about vaccines


Vaccination or immunization has been one of the discoveries that has benefited humanity the most. Since its discovery by Edward Jenner in 1789 with the smallpox vaccine the number of lives that have been saved is innumerable.

What is a vaccine?

A vaccine is an antigenic element (a part of the membrane or nucleus of either a virus or bacteria that produces an immune response or is antibodies) that is applied to an individual susceptible to acquiring an infection, with the aim of stimulating the specific inmune against this disease and thus generate future protection.

Types of vaccines

There are two main types of vaccines:

They are bacteria or viruses that have been physically or chemically weakened:
They do not tolerate heat
They generate immunogenicity with a single dose.
Two live vaccines should mostly be administered with a time interval greater than 28 days, if they are not administered simultaneously.
There is no maximum interval for the application of a second or third dose.
Dead or inactivated

Dead or inactivated
They are parts of viruses or bacteria
They do not tolerate freezing.
They require more doses to generate effect
They can mostly be given without a minimum interval of time between two inactivated vaccines.
There is no maximum interval for the application of a second or third dose.

It should also be understood that each vaccine has a different way of being administered. There are oral, intranasal, subcutaneous and intramuscular.

Are there any contraindications to vaccination?

The main contraindication for any vaccine is the presence of allergic reactions to components of the vaccine (such as an allergy to eggs).
On the other hand, there are a number of temporary contraindications such as the presence of fever on the day of vaccination, pregnancy, living with someone who is immunosuppressed or the presence of immunosuppression.
Something that is not a contraindication but a recommendation is the fact of not making an exchange between vaccines against the same disease but different manufacturer.

Side effects

General discomfort
In babies, unusual crying with no apparent cause
Swelling or pain at the local site
Skin rash (red lesions on the skin)
Ulceration and scar at the application site (in the case of BCG vaccines)
Appearance of symptoms of the disease that is intended to be prevented (this is very rare)

What is a vaccine failure?

Vaccination can fail and this occurs when a vaccinated person presents the infection that is intended to be prevented, it is considered of 2 types:

  • Primary: The vaccinated person did not produce antibodies when the vaccine was applied
  • Secondary: The vaccinated person presented antibodies but these disappeared from his blood after a while.

What are the vaccines in the immunization plan (for Colombia)?

The expanded immunization plan is the mandatory vaccines in Colombia, they are vaccines that are applied from birth to 5 years and prevent the most frequent infections:

  • BCG: Against Mycobacterium tuberculosis. Applies to birth.
  • ROTAVIRUS: Highly resistant virus in the environment can last days on surfaces or hands. It produces gastroenteritis (diarrhea and / or vomiting) that in infants can lead to hospitalization.
  • POLIOVIRUS: The vaccine is given orally, it generates herd immunity.
  • DPT: They are the acronyms of Diphtheria, Pertussis and Tetanus.
  • TRIPLE VIRAL: Includes measles, mumps and rubella. It should not be applied in pregnant women.
  • BACTERIA HAEMOPHILUS INFLUENZAE TYPE B: Bacteria responsible for a large number of serious respiratory diseases.
  • HEPATITIS B VIRUS: It should be applied at birth with the exception of babies weighing less than 2000 g.
  • YELLOW FEVER: Transmitted by mosquito bite, required to travel to certain areas.
  • INFLUENZA VIRUS: Virus that mutates very quickly so the vaccine is changed every year.
  • HEPATITIS A VIRUS: Illness that can present as gastroenteritis (diarrhea and / or vomiting) or asymptomatic.

Is any medication recommended before or after administering the vaccine?

The consumption of acetaminophen prior to the administration of vaccines is not recommended. However, if the vaccinated person has fever or pain, the drug can be administered.

What is herd immunity?

It is the fact that an unvaccinated person, being surrounded by vaccinated people, is protected from contracting the disease, it is observed with the vaccine against the Polio virus.


Merino Moína M, Bravo Acuña J. Generalidades sobre vacunas: cosas prácticas. En: AEPap (ed.).
Curso de Actualización Pediatría 2018. Madrid: Lúa. Ediciones 3.0; 2018. p. 67-76. de Pediatría, A. E. (2020). Manual de Vacunas en Línea de la AEP.
Lahariya, C. (2016). Vaccine epidemiology: a review. Journal of Family Medicine and Primary Care, 5(1), 7.

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