Sickle Cell Disease (SCD) is a condition that affects the shape of red blood cells. This study is checking if children with SCD develop enough protection after getting the measles vaccine. Infants with SCD who are due for this vaccine will be contacted. Some will be checked after their first vaccine (MV1) and others after their second (MV2).

Blood samples will be taken before the vaccine and then again 4 and 8 weeks later. This will help researchers understand how well the vaccine works in these children.

• The study involves taking blood samples before and after the measles vaccine.
• Children between 6 months and 6 years old with SCD who need the measles vaccine can join.
• Participants should not have other conditions that prevent them from getting live vaccines, like AIDS or cancer.

Participating means you will need to visit the study location for evaluations and follow-up visits. It's important to understand that this study is focused on safety and effectiveness of the vaccine for kids with SCD.