My mother is president of her condo board, and specializes in condo law; and this is not legal (at least at this time). She's in Canada though so it may be different than the US, and the rules are changing. However, as of now, they are not legally able to shut down the building to visitors, prevent people from leaving, limit the occupancy of elevators, require people to submit health information, etc. (and a number of residents have asked for these things). They can, however, close fitness/recreation rooms and forbid people from congregating in common areas (which is currently Provincially-mandated for everyone). It is inappropriate (and illegal under HIPAA) for a condo board (seriously??) to demand health information from residents, and I would not comply with this request. In fact, your condo board may be inviting liability by seeking to control this (i.e. if they assume responsibility for keeping people healthy and behave as such, they can be sued if they fail and someone becomes ill). Everyone in your building should assume that they have been exposed to the coronavirus and behave accordingly to protect themselves.
I'm not a lawyer but I've been calling my mom daily to help alleviate some of her isolation (lives alone, working from home), and this is all. she. talks. about. There are a plethora of webinars from condo lawyers on this topic (apparently). If your board starts mandating building-wide quarantines and the like, I would absolutely push back and/or seek guidance from a reliable legal source.