Chronic diseases may make children more susceptible to the severe manifestations and complications of common infections. Unless specifically contraindicated, immunizations recommended for healthy children should be given to children with chronic diseases. An exception is children with immunologic disorders in whom live-virus vaccines usually are contraindicated; the major exceptions are MMR and varicella vaccines for HIV-infected children who are not severely immunocompromised (see Immunocompromised Children). For children with conditions that may require organ transplantation or immunosuppression, administering recommended immunizations before the start of immunosuppressive therapy is important. Children with certain chronic diseases (eg, cardiorespiratory, allergic, hematologic, metabolic, and renal disorders; cystic fibrosis; and diabetes mellitus) are at increased risk of complications of influenza, varicella, and pneumococcal infection and should receive inactivated influenza vaccine and live varicella vaccine and/or pneumococcal conjugate or polysaccharide vaccine as recommended for age and immunization status (see Influenza, Varicella-Zoster Infections, and Pneumococcal Infections). People with chronic liver disease are at risk of severe Clinical Manifestations of acute infection with hepatitis viruses and should receive hepatitis A and hepatitis B vaccines on a catch-up schedule if they have not received vaccines routinely (see Hepatitis A) and (see Hepatitis B). Siblings of children with chronic diseases and children in households of adults with chronic diseases should receive recommended vaccines (see Fig 1.1-1.3 and (see Immunocompromised Children).