RESUMO
Yokohama city started a regular, free vaccine program for Haemophilus influenzae type b (Hib) from February of 2011. This study was completed to verify the effectiveness of the vaccine on the nasopharyngeal Hib carriage among healthy children attending daycare centers in the Isogo area. The research was conducted during the late spring (Jun--Jul) and fall (Oct-Nov) of 2012. There was a significant decrease in the Hib carriage rate (spring 8.8%, fall 1.6%). During this period there was no increase in the Hib vaccine coverage. The Hib carriage rate of each daycare center was 0-18.4% in spring and 0-4.9% in fall. There was no significant relationship between the rate of non immunized children and that of Hib carriage. This improvement in nasopharyngeal Hib carriage shows the impact of community immunity.
