The impact of community-based outreach immunisation services on immunisation coverage with GIS network accessibility analysis in peri-urban areas, Zambia.
BACKGROUND
Accessibility to health services is a critical determinant for health outcome.


OBJECTIVE
To examine the association between immunisation coverage and distance to an immunisation service as well as socio-demographic and economic factors before and after the introduction of outreach immunisation services, and to identify optimal locations for outreach immunisation service points in a peri-urban area in Zambia.


METHODS
Repeated cross-sectional surveys were conducted for two groups of children born between 1999 and 2001, and between 2003 and 2005.The association between immunisation coverage for DPT3 and measles, and access distance, child sex, female headed households, and monthly household income were assessed using logistic regression analysis. Optimal locations for outreach service points were identified using GIS network analysis and genetic algorithms.


RESULTS
Before the introduction of outreach services, longer distances to the service points were associated with lower DPT3 and measles immunisation coverage (OR=0.24, 95% CI 0.10 to 0.56, p<0.01 for DPT3; and OR=0.38, 95% CI 0.17 to 0.83, p<0.05 for measles). However, access distances were not an impediment to immunisation coverage once the outreach services were introduced. The average distance to immunisation services could be decreased from 232.3 to 168.4 metres if the current 12 outreach service points were repositioned at optimal locations.


CONCLUSIONS
Access distance to immunisation services was a critical determinant of immunisation coverage in a peri-urban area. Intervention via outreach services played an important role in averting the risk of missing out on immunisation. Optimal location analysis has the potential to contribute to efficient decision making regarding the delivery of immunisation services.
Sasaki
Satoshi
S
School for Excellence in Undergraduate Education, Soka University, 1-236 Tangi-machi, Hachioji-shi, Tokyo, Japan. satoshi@soka.ac.jp
Igarashi
Kumiko
K
Fujino
Yasuyuki
Y
Comber
Alexis J
AJ
Brunsdon
Chris
C
Muleya
Clala Mbwili
CM
Suzuki
Hiroshi
H
D002648:Child; D003153:Community Health Services / Q000458:organization & administration / Q000706:statistics & numerical data*; D003159:Community-Institutional Relations; D003430:Cross-Sectional Studies; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage; D005191:Family Characteristics; D005260:Female; D040362:Geographic Information Systems; D006297:Health Services Accessibility / Q000706:statistics & numerical data*; D006801:Humans; D007114:Immunization / Q000706:statistics & numerical data*; D017589:Immunization Programs / Q000458:organization & administration*; D008297:Male; D008458:Measles Vaccine / Q000008:administration & dosage; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data; D015397:Program Evaluation; D012044:Regression Analysis; D012959:Socioeconomic Factors; D014505:Urban Population; D015024:Zambia
D015721:Diphtheria-Tetanus-Pertussis Vaccine; D008458:Measles Vaccine