Morally obligated, yes. Legally obligated, not in the least.

In the US, unless a judge has ordered you to receive medical attention, there is no way to force someone to consent to medical treatment. You can't force someone who is bi-polar to take lithium, can't force someone who needs glasses to wear them, can't force someone who is a high heart attack risk to get his blood pressure and cholesterol down. And you can't, as the law stands now (and there are a number of Constitutional issues at play) force someone to go into a quarantine unless a judge decides they are a clear and present danger to the population as a whole.

Don't be surprised if that changes soon. It will be the law of the land for a few years while it percolates upstream in the federal court system.