"Children with sickle cell disease are hospitalized about once a year for pain crises and other complications, so we should do everything we can to prevent hospitalization from the flu by using safe and effective vaccines," says lead investigator John J. Strouse, M.D. Ph.D., a pediatric hematologist at Hopkins Children's.

Named for the unusually sickle-shaped red blood cells caused by a genetic abnormality, sickle cell anemia affects nearly 100,000 Americans. The cells' abnormal structure reduces their oxygen delivery to vital organs and causes them to get stuck in the blood vessels, leading to severe pain and so-called "sickling crises," which require hospitalization.

The CDC recommends that all children over 6 months of age get seasonal and H1N1 flu shots, except those who are allergic to eggs or have had a severe reaction to a flu vaccine in the past.