You may want to send out an email to friends who have used it in the past to let them know the apt isn't going to be available anymore, just to avoid any guilt trips if they say "But I already bought my plane tickets and was counting on it!" or other potential arguments. I wouldn't give any reasons, but a generic "it's not possible".
I hope this email finds you well. As a friend/relative who has used our NYC apartment in the past, we just wanted to let you know that unfortunately we aren't able to have guests there for the foreseeable future. With the holidays and New Year approaching, we wanted to let everyone know now, in case you were planning a trip and need to make alternate plans for accommodations.