Effect of infant immunisation on childhood mortality in rural Bangladesh: analysis of health and demographic surveillance data.
BACKGROUND
In developing countries, immunisation programmes must compete with other strategies to improve public health and quality of life. Studies of long-term effects of immunisation programmes are rare. We assessed associations between vaccinations and mortality over 15 years after the introduction of routine infant immunisation programmes in Matlab, Bangladesh.


METHODS
We analysed data recorded in a comprehensive health and demographic surveillance system from 1986 to 2001. We did univariate analyses and assessed vaccinations as independent factors with other variables in Cox models with time dependent covariates.


RESULTS
Diphtheria-tetanus-pertussis (DTP) and oral polio vaccination were independently associated with decreased risk of death before age 9 months, as were amount of maternal education, maternal age, and birth order of the child. DTP vaccination was associated with increased survival (hazard ratio=0.76, 95% CI 0.67-0.88; p=0.001) in a model evaluating mortality between 6 weeks and 9 months of age. Measles vaccination was also associated with increased survival when data after late immunisation with DTP and Bacille Calmette-Guérin (BCG) were excluded. BCG vaccination was associated with reduced survival; however, children vaccinated with BCG during the first 6 months of life had significantly lower risk of death than those vaccinated later (hazard ratio=0.59; 95% CI 0.47-0.73; p=0.0001).


CONCLUSIONS
By contrast with previous findings, we noted substantially reduced mortality among children who received DTP vaccine. This effect could be due to actual protection against pertussis disease and secondary illnesses or to a non-specific benefit, although we cannot rule out epidemiological artifact. Our findings show the value of population-based health surveillance systems.
Breiman
Robert F
RF
International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh. rbreiman@cdc.gov
Streatfield
Peter Kim
PK
Phelan
Maureen
M
Shifa
Naima
N
Rashid
Mamunur
M
Yunus
Mohammed
M
D001500:BCG Vaccine / Q000008:administration & dosage; D001459:Bangladesh / Q000453:epidemiology; D001722:Birth Order; D002675:Child, Preschool; D003906:Developing Countries / Q000706:statistics & numerical data; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage; D004522:Educational Status; D005260:Female; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D008458:Measles Vaccine / Q000008:administration & dosage; D011055:Poliovirus Vaccine, Oral / Q000008:administration & dosage; D016016:Proportional Hazards Models; D012423:Rural Health; D014611:Vaccination / Q000009:adverse effects / Q000706:statistics & numerical data
D001500:BCG Vaccine; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D008458:Measles Vaccine; D011055:Poliovirus Vaccine, Oral