i had my kids this past weekend. was fine. this is the type of excuse your ex could use to stop you taking the kids. don't give her that idea. people are being super paranoid now.collect your son by car if possible and just keep him at home.
No one is sure how long the epidemic could last, the last thing you want to do is not have your kid then that sets a precedent with the ex. Keep the kids coming but exercise the usual precautions that the situation requires.