A 32-year-old woman is evaluated for an URTI. She was well until 5 days ago when she developed a fever, sore throat, nonproductive cough, and runny nose. She has no ear pain or nasal congestion. Her PMH is otherwise unremarkable. She has no allergies and takes no medications. She lives at home with her husband and 8-yearold twin boys. On examination, her vital signs are normal. Her ears, nose and oropharynx appear normal. She has no lymphadenopathy, and her lungs are clear to auscultation. Which of the following is the best prevention strategy for her family?