If this is what omicron feels like with a vaccine, you may be thanking your lucky stars that you got your shots. Despite all the guidelines helping people to distinguish between the two, a positive rapid antigen test is still the only surefire way of knowing which illness you have.

Early in the pandemic, our immune systems fought the coronavirus and we felt ill. Without any preexisting immunity we likely had a large amount of virus in our systems by the time we felt rotten.

Vaccines were a game changer. Michael Mina, an epidemiologist, says feeling sick can be a good thing. Vaccines help our immune system to more quickly recognize and fight the virus, and that makes us feel sick — not necessarily the virus load. Mina said you can be symptomatic and pre-infectious, infectious, post-infectious or never infectious.

A high, but unspecified number, had booster shots. The results were concerning, particularly as millions of people rely on at-home antigen tests. As a result, four participants spread the virus before discovering they were positive. Isolate and test with symptoms.

But when do you exit isolation? How do you interpret those rapid tests? One red line is negative, while two red lines means positive.

COVID Symptoms Timeline: Signs to Expect With the Virus and When

When and how you exit isolation has just gotten trickier. But it does not require it. This stance has divided public opinion, and frustrated some epidemiologists.