Declining antibody levels after hepatitis B vaccination in Down syndrome: A need for booster vaccination?

We determined the anti-HBs titer in 227 children of all ages with Down syndrome (DS). Only 48.1% (95%CI: 35.1-61.3) of the DS children aged 7-10 years and 31.9% (95%CI: 22.1-43.6) of the DS children aged >10 years had a protective anti-HBs titer (≥10 IU/L). The geometric mean anti-HBs titer was significantly lower in the DS children; this suggests booster vaccination for HBV may be needed.