Spatial access inequities and childhood immunisation uptake in Kenya

Abstract

Background: Poor access to immunisation services remains a major barrier to achieving equity and expanding vaccination coverage in many sub-Saharan African countries. In Kenya, the extent to which spatial access affects immunisation coverage is not well understood. The aim of this study was to quantify spatial accessibility to immunising health facilities and determine its influence on immunisation uptake in Kenya while controlling for potential confounders.

Methods: Spatial databases of immunising facilities, road network, land use and elevation were used within a cost friction algorithim to estimate the travel time to immunising health facilities. Two travel scenarios were evaluated; (1) Walking only and (2) Optimistic scenario combining walking and motorized transport. Mean travel time to health facilities and proportions of the total population living within 1-h to the nearest immunising health facility were computed. Data from a nationally representative cross-sectional survey (KDHS 2014), was used to estimate the effect of mean travel time at survey cluster units for both fully immunised status and third dose of diphtheria-tetanus-pertussis (DPT3) vaccine using multi-level logistic regression models.

Results: Nationally, the mean travel time to immunising health facilities was 63 and 40 min using the walking and the optimistic travel scenarios respectively. Seventy five percent of the total population were within one-hour of walking to an immunising health facility while 93% were within one-hour considering the optimistic scenario. There were substantial variations across the country with 62%(29/47) and 34%(16/47) of the counties with < 90% of the population within one-hour from an immunising health facility using scenarios 1 and 2 respectively. Travel times > 1-h were significantly associated with low immunisation coverage in the univariate analysis for both fully immunised status and DPT3 vaccine. Children living more than 2-h were significantly less likely to be fully immunised [AOR:0.56(0.33-0.94) and receive DPT3 [AOR:0.51(0.21-0.92) after controlling for household wealth, mother's highest education level, parity and urban/rural residence.

Conclusion: Travel time to immunising health facilities is a barrier to uptake of childhood vaccines in regions with suboptimal accessibility (> 2-h). Strategies that address access barriers in the hardest to reach communities are needed to enhance equitable access to immunisation services in Kenya.

Keywords: Equity; Health facilities; Immunisation; Kenya; Spatial accessibility.

Fig. 1

Spatial accessibility to the nearest immunising health facilities in Kenya based on two travelling scenarios. a Scenario 1; Walking only b Scenario 2; Optmistic (a combination of walking and any motorized transport). Travel time is categorized into 15 min bands ranging from < 15 min (dark green) to 120+ minutes (red). Grey areas represent protected areas whose names and designate are provided in additional file 1. (Source: Authors)

Fig. 2

Catchment population and travel time at county units. a Proportion (%) of catchment population within one-hour to immunising health facilities at county units based on the optimistic travel scenario. Proportion estimates are grouped into four categories as follows; < 50% (red), 50- < 80(brown), 80- < 90 (light green) and 90+ (green) and grey areas represent protected areas whose names and designate are provided in additional file 1b Distribution of travel times within each county capped at 2 h using the optimistic travel scenario. Height of the bars indicate the level of variation in travel time within a county. Scatter dots represent mean travel time in each county. (Source: Authors)