Benefits of routine immunizations on childhood survival in Tari, Southern Highlands Province, Papua New Guinea.
BACKGROUND
Non-specific beneficial as well as deleterious effects of childhood immunizations have been reported in areas of high mortality. This study aimed to determine the effects of diphtheria-tetanus-whole-cell-pertussis (DTP), BCG, hepatitis B, and measles vaccines on mortality in the highlands of Papua New Guinea (PNG).


METHODS
Demographic events for children born in 1989-1994 who were under monthly demographic surveillance in Tari were recorded from birth until age 2 years, out-migration, death, or the end of the study period. Data on BCG, hepatitis B, DTP, measles and pneumococcal polysaccharide vaccination were collected monthly from clinic records. To allow for different characteristics of immunized and non-immunized children, analysis included conditioning on a propensity score for vaccination, adjusting for differences in children's background characteristics.


RESULTS
In all, 101/3502 children (3%) who had at least one vaccine died between ages 29 days and 24 months were compared to 112/546 (21%) who had none. BCG was associated with lower mortality in the 1-5 month age group (hazard ratio [HR] = 0.17, 95% CI: 0.09, 0.34), measles vaccine with lower mortality at age 6-11 months (HR = 0.42, 95% CI: 0.17, 1.01), and pneumococcal polysaccharide vaccine with lower mortality at age 12-23 months (HR = 0.42, 95% CI: 0.19, 0.93). One or more doses of DTP was associated with lower overall mortality (HR = 0.27, 95% CI: 0.16, 0.44), particularly in the 1-5 month age group (HR = 0.19, 95% CI: 0.10, 0.34), and also in those who had had prior BCG (HR = 0.45, 95% CI: 0.22, 0.91).


CONCLUSIONS
Routine immunizations are effective in reducing overall mortality in young children in an area of high mortality. In particular, DTP, whether considered separately or in addition to BCG, was associated with a lowering of overall mortality, in contrast to findings reported from Guinea-Bissau.
Lehmann
Deborah
D
Papua New Guinea Institute of Medical Research, Goroka and Tari, Papua New Guinea. deborahl@ichr.uwa.edu.au
Vail
John
J
Firth
Martin J
MJ
de Klerk
Nicholas H
NH
Alpers
Michael P
MP
D001500:BCG Vaccine / Q000008:administration & dosage; D003906:Developing Countries; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage; D005260:Female; D017325:Hepatitis B Vaccines / Q000008:administration & dosage; D006801:Humans; D017589:Immunization Programs; D007115:Immunization Schedule; D007223:Infant; D007226:Infant Mortality; D008297:Male; D032541:Mass Vaccination; D008458:Measles Vaccine / Q000008:administration & dosage; D010219:Papua New Guinea / Q000453:epidemiology; D015397:Program Evaluation; D012189:Retrospective Studies; D016019:Survival Analysis
D001500:BCG Vaccine; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D017325:Hepatitis B Vaccines; D008458:Measles Vaccine