What is Lay Epidemiology?

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Before diving into lay epidemiology, let us first define epidemiology by itself. Epidemiology is the study of the distribution, causes, and risk factors of diseases and other health-related events in and among populations. A key part of this definition is that the evaluation is occurring at the population level. The findings from these evaluations then influence how vaccination programs, quarantine protocols, and emergency relief efforts are carried out. 

However, for these programs to be successful it seems that more perspectives need to be considered. In a study surveying Danish parent’s decision on whether to allow their child to receive the BCG vaccine* against Tuberculosis, researchers found that a new phenomenon called “lay epidemiology” is an important factor in the decision.

 *Note: The BCG vaccine is not required nor typically given in the United States.

What is lay epidemiology? How does it influence your decision to get vaccinated?

Lay epidemiology is described as making a risk evaluation on an individual level. More specifically, the attitudes, beliefs, and experiences regarding the cause and distribution of illness in one’s family or local social network influence an individual’s assessment of risk. For example, the statement “I do not get the flu vaccine because my friend had a bad reaction one time” was a decision shaped by lay epidemiology. 

Researchers in the Demark study found that when parents were asked about how a negative reaction to the BCG vaccine within their family or friend group would affect their own decision to get their child vaccinated, many answered that yes someone else’s bad experience would definitely affect their decision. Especially, if that person was close to them. However, it is also important to note that lay epidemiology can influence decisions in support of a vaccine too. Overall, lay epidemiology is using your own experiences or the experiences of those closest to you to determine if something is safe for you or your child.


Now, with the knowledge of this phenomenon and the understanding that it has a strong impact on a person’s decision regarding vaccines, it is important that the individual level risk assessments of lay epidemiology be considered alongside population level risk assessments of scientific epidemiology when creating health messages and vaccine campaigns. It is stressed that lay epidemiology not be seen as a barrier, but an addition of knowledge to improve current programs. People want to know how a vaccine or other health intervention will impact their individual lives, as well as the population (Phil et al., 2017).

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