Fig 1.
The study districts in south-east Tanzania where mass dog vaccinations and post-vaccination transects were undertaken.
Shapefiles to make this figure were downloaded from the Diva GIS data portal (https://www.diva-gis.org/).
Table 1.
Characteristics of the study districts where mass dog vaccinations and post-vaccination transects were conducted between 2010 and 2017.
Table 2.
Showing summary of data from 2,066 vaccination units over a 7-year period showing explanatory variables hypothesised to be associated with completeness and coverage.
Statistics reported separately for vaccination units with and without completed vaccination campaigns, and with low and high coverage respectively. All these statistics were calculated at the vaccination unit-level. N = number; TZS = Tanzanian shillings; VU = vaccination unit; HQ = headquarters.
Fig 2.
(a) The number of dogs vaccinated and overall coverage across the study area from 2010 to 2017 and (b) detail on the number of dogs vaccinated in each district. Coverage was calculated from the monthly estimated total number of vaccinated dogs divided by the estimated monthly total dog population estimate (blue line). The number of dogs vaccinated in each district each month ranged from 0 to 13 thousand dogs, indicated by the “heat intensity” of the colours from white to red (maximum).
Table 3.
Summary of the performance of vaccination campaigns in terms of completeness, coverage and timeliness for the 25 study districts over the five rounds of vaccinations from 2010–2017.
Fig 3.
Coverage achieved in the five rounds of vaccination campaigns at the level of the vaccination unit.
Coverage for rounds 1 and 2 was calculated using projected dog population estimates, while coverage for rounds 3–5 coverage were estimated as explained in the Methods. Darker green shading corresponds to higher coverage while white shading indicates that no vaccination campaign was undertaken. Hatched represents forest reserves or wildlife-protected areas. Shapefiles to make this figure were downloaded from the Diva GIS data portal (https://www.diva-gis.org/).
Fig 4.
Coverage achieved during campaigns in each district from 2013 to 2017 (third to fifth round of vaccinations) calculated directly from transects without accounting for the pup:adult ratio (PAR) and excluding villages without transect data.
Black diamonds represent mean coverage across the three rounds. The black dashed line represents the target 70% vaccination coverage threshold.
Fig 5.
The campaign timeliness in each of the five regions from 2010 to 2017.
The target coverage (Ptarget) of 70% was not achieved in all regions (upper red line), and between campaigns coverage declined due to dog population turnover. When annual campaigns achieved high coverage, coverages were sustained above the critical immunity threshold (below the red line labelled Pcrit) for approximately 12 months. The time lag between campaigns (up to >20 months), caused coverage to decline below Pcrit. Mean coverage across all district in the regional was calculated from the number of vaccinated dogs in each region divided by the number of estimated dogs in each region.
Fig 6.
Required vaccination campaign intervals to prevent coverage falling to critical levels.
For the populations in Tanzania, 66% coverage should maintain herd immunity above Pcrit of 30% for 12 months, assuming the use of high-quality vaccines (as used in this study) where the average duration of vaccine-induced immunity is 3 years.
Table 4.
Odds ratio (OR) estimates of characteristics of vaccination units (predictors) and the success of rabies vaccination campaigns in terms of coverage and completeness.
OR and 95% confidence intervals (CIs) were estimated using binomial generalised linear mixed-effects models (GLMMs). Each predictor was fitted separately in univariable models, adjusted only for random effects and round, and combined in a mutually adjusted multivariable model. Non-significant predictors were removed from the model in a single round of model selection (see main text for details).