It is a common misconception — in some cases used as subterfuge — that whether or not a question is on-topic or not can be determined by a discussion on Meta as to whether questions about such-and-such a subject are or are not on topic. To find out what subjects in biology are on topic one needs to consult the Tour which lists:
- general questions about biological concepts
- questions about the biological mechanisms behind medical conditions
- questions about techniques in a biological or biochemical laboratory
Questions of the following types, even though on the acceptable topics listed above, can still be off-topic:
- Anything not directly related to biology, such as personal medical questions.
- Philosophical or ethical questions related to biology
- Questions that are primarily opinion-based
- Questions with too many possible answers or that would require an extremely long answer
This is repeated and slightly elaborated on in this Help, and types of questions to avoid asking are described in this Help.
One should also bear in mind that the supposed objective of the site is to “build a library of detailed answers to every question about biology”, and, although this is actually Stack Exchange boiler plate, it emphasizes that the focus is on questions that have value beyond the moment. That is one of the reasons why I regard the question quoted as off-topic: “Where are we right now between scenario A and scenario B?” can have no lasting value.
I can imagine a question on epidemiology being on topic if the question relates to the biological content — the mechanism of spread, the reasons for the plateau and fall etc. However something that is purely mathematics or statistics does not fill this bill. Questions of this sort are better posted to SE Medical Sciences or Statistics, where they can be appraised by a more expert audience.
Hence my answer to the question is:
The area of subject matter cannot establish that a question is on-topic (although it can indicate whether it is off-topic, e.g. about physics rather than biology). Some questions about Epidemiology my be considered to be about biology, although many will not. Such questions may still be off-topic if they violate other criteria, such as soliciting discussion or opinion.