What does working in a wet lab, or PCR, have to do with having knowledge of an epidemiological concept, or being an epidemiologist? Basically, epidemiologists collect and analyze data on disease determinants and some perform or recommend interventions based on that analysis. Those diseases can be chronic or acute, infectious or environmental.
Most professional epidemiologists have never worked in a wet lab, nor do they have medical degree (some epidemiologists do, but it's less common). Likewise, most doctors have zero formal training in epidemiology. A few medical schools have integrated a module on biostatistics and epidemiology into their curriculum, but it's not common (or at least it wasn't ~20 years ago, if that's changing I'm happy). I'm always amazed at how many doctors fail to understand basic biostatistical measures used in epidemiology and biostatistics, such as specificity and sensitivity, much less positive predictive value (also very important to know when interpreting test results like doctors do every day).
As we know on HN, people tend to misunderstand what computer scientists do. They assume they're more or less programmers, when in fact, they're doing a kind of applied math in a specific domain. In the same way, people misunderstand what epidemiologists do. They assume they're all doctors working on infectious diseases. In fact, you could look at epidemiology as also being a kind of applied math in a specific domain (population health).
(if it matters, I did a master's degree in epidemiology many years ago, and worked briefly on epidemiological grant research for a university. I changed professions soon afterwards, and have forgotten most of what I learned. But I do have a good idea of how epidemiologists are trained, and what they do on a daily basis.)
