This is a good question. I broke a bone in my foot last year, and then developed a high blood pressure problem, and I missed months of classes. At first I continued my stretching exercises and did a home barre (no room for center in my small apartment) (you can buy ballet music for barre (and center) from most dancestores), but then the blood pressure medication started working and I got lethargic and away from my home barre (I bought it years ago and it has moved everywhere with me).
In the past during vacations I have always tried to keep up at least a barre routine; I even do barre when I travel, in hotel rooms, using a chair.
As for my present state, I had the doc change my meds, and started a home barre again. And my blood pressure dropped.
In my opinion, it is important to keep up the routine when faced with a vacation or faced with a school closure (for vacation). It's easy to do, and you can get barre music (most discs have double music for right and left), and typically a chair will work for the barre. The floor may not be ideal (e.g. rigs), but eke out a space for yourself.
balletboy[/i]