ABSTRACT
BACKGROUND: Many reports about the preventative effects of inactivated influenza vaccine have been published, targeting persons with underlying medical conditions. However, the effectiveness for severely multiply handicapped persons/children (SMHPs) is not yet well established. METHODS: The study group consisted of 79 SMHPs (36 males and 43 females, aged 18-66 years), with long-term hospitalization in Niigata National Hospital. We compared serum antibody responses before and after two-doses vaccination. RESULTS: Before vaccination for the 2004-2005 season, SMHPs showed continuously high HAI titer in A/New Caledonia/20/99(H1N1)-strain from March to October in 2004. The seroprotection rates were increased after the first dose, but no remarkable change was seen after the second dose in all three strains. Subjects less than 30 years old (< or = 29 group) had a high antibody titers against all three strains compared with subjects aged >40 years old. On the other hand, in the seroconversion rates, there were no significant differences in age, gender, and severity of symptoms. CONCLUSIONS: According to our study, SMHPs are low responders except < or = 29 group and the influenza vaccine effectiveness is more affected by their age than severity of symptoms. We suggest a recommendation for influenza vaccination especially in SMHPs; inactivated influenza virus vaccine (one dose) should be performed during the previous fall. In addition, further studies are needed about chemoprophylaxis, which can prevent influenza outbreaks in SMHPs.
