Immune response to 1 and 2 dose regimens of measles vaccine in Pakistani children.
Measles is a significant problem in Pakistan despite vaccine coverage rates reported at 80%. The purpose of this study was to determine the serologic response in children after one dose of measles vaccine at 9 mo versus two doses at 9 and 15 mo of age. From March through December 2006, children were enrolled from immunization clinics and squatter settlements in Karachi. Blood samples were taken from children in Group A at 9-10 mo of age prior to measles vaccine and 8 to 11 weeks later; from children in Group B at 16-17 mo of age after receiving 2 doses of measles vaccine; and from children in Group C who had received at least one dose of measles vaccine by 5 y of age. After the first dose of measles vaccine, 107/147 (73%) of children in Group A were seropositive, 157/180 (87%) of children in Group B were seropositive after two doses and 126/200 (63%) of children in Group C were seropositive at 5 y of age. The post-vaccination geometric mean antibody concentrations were higher in females than males in groups A (irrespective of pre-vaccination antibody levels) and B. The serologic response to one and two doses of measles vaccine was lower in children in Karachi than has been reported in many other countries. Two doses of vaccine were significantly better than one dose. An in-depth investigation is needed to determine the reason for the lower-than-expected protection rates. Differences in immunogenicity between genders need to be further studied. Recent introduction of supplemental measles vaccine doses should help control measles in Pakistan.
Department of International Health; Johns Hopkins Bloomberg School of Public Health; Johns Hopkins University; Baltimore, MD USA; Interactive Research and Development; Karachi, Pakistan.
Hamidah
H
Hussain
Health Education and Literacy Programme (HELP); Karachi, Pakistan.
Dure Samin
DS
Akram
Department of International Health; Johns Hopkins Bloomberg School of Public Health; Johns Hopkins University; Baltimore, MD USA.
Subhash
S
Chandir
Department of International Health; Johns Hopkins Bloomberg School of Public Health; Johns Hopkins University; Baltimore, MD USA; Interactive Research and Development; Karachi, Pakistan.
Aamir J
AJ
Khan
Kharadar General Hospital; Karachi, Pakistan.
Ashraf
A
Memon
Department of International Health; Johns Hopkins Bloomberg School of Public Health; Johns Hopkins University; Baltimore, MD USA.
Neal A
NA
Halsey
D000914:Antibodies, Viral / Q000097:blood*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008457:Measles / Q000276:immunology / Q000517:prevention & control*; D008458:Measles Vaccine / Q000008:administration & dosage* / Q000276:immunology*; D010154:Pakistan; D012737:Sex Factors; D016896:Treatment Outcome; D014611:Vaccination / Q000379:methods*
D000914:Antibodies, Viral; D008458:Measles Vaccine
Measles vaccine; Pakistan and Geometric mean titers; measles vaccine effectiveness; serologic response