A group of doctors is trying to see if a vaccine causes a certain type of disease. They take individuals with the certain disease and individuals without the disease. They then use research to estimate the relative incidence of the onset of the disease after the vaccination. What kind of study is this called.
I'm up in the air if it would be a Cohort study or Case-Control study.
Thinking it could be Cohort because they are two separate groups being compared to the disease. However, I'm also thinking Case-Control because the disease has already occurred.
Any help or more explanation on these two studies please.
http://www.gfmer.ch/Books/Reproductive_health/Cohort_and_case_control_studies.html
Based on the information given, the study you described is a case-control study.
In a case-control study, researchers compare individuals with a certain outcome (in this case, the disease) to those without the outcome. In this study, they take individuals who have the certain disease (cases) and individuals who do not have the disease (controls).
The next step in a case-control study is to look back in time to determine the exposure status of each group. In this case, the exposure of interest is the vaccination. The researchers then compare the frequency of vaccine exposure in the case group (those who have the disease) to the control group (those who do not have the disease) to estimate the relative incidence or association between the vaccination and the onset of the disease.
In contrast, a cohort study starts with a group of individuals who are exposed or not exposed to a particular factor (in this case, the vaccine) and follows them over time to determine the development of the disease. In a cohort study, the exposure comes before the outcome.
In summary, based on the information provided, the study you described is a case-control study because it compares individuals with and without the disease and looks back in time to determine their exposure status to the vaccine.