Yes, this is true. There are some uncommon circumstances when certain people should not be given vaccines such as those who are getting cancer chemotherapy or those with immune deficiencies. However, vaccine-preventable diseases can cause serious complications in people who have chronic illnesses, such as influenza in those who have asthma, heart disease, cancer, and diabetes. Most children who have minor illnesses can still get their recommended vaccines depending on which vaccine is needed and the type and severity of the illness. Talk with your health care provider and learn more about the vaccines recommended for your child's age, health status, and lifestyle, especially if you have a chronic or serious health condition.