Key Findings
The 2010-2017 mass dog vaccination campaigns in southeastern Tanzania faced difficulties in consistently achieving high coverage, particularly in vaccination units with larger dog populations and in rural areas. Additionally, campaigns conducted during the dry season saw lower completeness and coverage compared to those in the wet season.
Monitoring was not implemented until 2013, leaving organizers unaware that vaccination efforts were heavily focused on urban areas while remote villages were often neglected.
Bureaucratic delays in securing funding and vaccines prevented the annual scheduling of campaigns, resulting in intervals of up to 27 months between them.
Summary
Human rabies deaths can be entirely prevented through two key interventions: post-exposure prophylaxis (PEP) for those bitten by suspected rabid animals and mass dog vaccinations (MDV) to eliminate the primary source of infection. Annually, over 29 million people receive PEP. But it is costly, with total expenditures exceeding $3 billion. The burden of rabies, both in terms of disease and cost, disproportionately affects rural communities, where access to PEP is often limited due to financial barriers and supply shortages.
While PEP is effective, it cannot eradicate rabies alone; MDV is also crucial. Mass dog vaccination programs have successfully eliminated dog-mediated rabies in industrialized countries and are effective even in low-income regions. To monitor the effectiveness of MDV campaigns, key metrics include campaign completeness, achieving at least 70% vaccination coverage, and conducting timely follow-up campaigns within 12 months to maintain herd immunity.
In Tanzania, rabies is endemic, causing an estimated 552 human deaths annually, with domestic dogs being the primary source. In 2010, Tanzania launched the Rabies Elimination Demonstration Project, a large-scale dog vaccination initiative in the southeast, supported by the WHO and the Bill and Melinda Gates Foundation. This study, titled “Scaling-up the delivery of dog vaccination campaigns against rabies in Tanzania”, evaluates the coverage, completeness, and timeliness of dog vaccinations delivered through this project from 2010 to 2017, identifying factors that influenced campaign success.
Methods
The study was conducted in 25 districts across five regions in southeastern Tanzania: Lindi, Mtwara, Pwani, Dar es Salaam, and Morogoro. These districts include rural, coastal, and urban areas, and had a combined population of approximately 8.5 million people. Between 2010 and January 2017, five rounds of MDV campaigns were conducted. On the vaccination day, detailed records of each vaccinated dog were kept, and owners received vaccination certificates. Vaccinated dogs were fitted with temporary collars for identification during post-vaccination assessments.
Although MDV started in 2010, monitoring and evaluation of the campaigns only began in 2013, using transects to assess vaccination coverage. Transects were conducted on the same day as the campaigns, with enumerators counting marked (vaccinated) and unmarked (unvaccinated) dogs. In rural areas, transects were conducted in randomly selected sub-villages, while in urban areas, they covered specific streets. Enumerators were trained community members familiar with the local areas, and their data was used to calculate vaccination coverage. The introduction of transects significantly improved campaign monitoring, helping identify areas with poor or missed coverage.
Results
Completeness & Coverage
The 2010-2017 MDV campaigns in southeastern Tanzania faced challenges in achieving consistent, high coverage. Despite vaccinating 349,513 dogs across 2,066 units, only 19-21% of vaccination units achieved the recommended 70% coverage during the monitored rounds (Rounds 3 to 5). District-level coverage varied widely, from 31% in Masasi Township to 83% in Rufiji, with only one out of 25 districts consistently reaching the 70% target.
While improvements were observed over time, the initial performance highlighted the difficulties of implementing these campaigns in regions with limited experience. Monitoring campaigns proved crucial for identifying gaps in coverage and guiding targeted interventions. From 2010 to 2013, before monitoring began, vaccinations were concentrated in urban areas, neglecting remote villages. Transect surveys addressed this issue, leading to improved coverage. As such, the researchers recommend rapid assessments to ensure all areas are covered and to achieve high vaccination coverage.
Vaccination Intervals
Inconsistent vaccination intervals and delays due to funding and vaccine shortages further hindered efforts. Vaccination campaigns did not consistently occur at the recommended 12-month intervals, leading to significant declines in coverage between rounds. For example, the median interval between the first and second rounds was 16 months, and delays of up to 18 months occurred due to funding issues. The third round saw even longer intervals, up to 27 months, due to vaccine shortages. Timeliness improved in the fourth and fifth rounds with better vaccine procurement.
Analysis indicated that if campaigns were conducted annually, then at least 66% vaccination coverage is needed to prevent coverage from dropping below 30% before the next annual campaign. If coverage falls below this threshold, then even more frequent campaigns are necessary; for instance, 50% coverage would require campaigns every seven months.
Scaling up infectious disease control campaigns demands strong coordination, infrastructure, and capacity for timely vaccine or drug procurement and effective delivery to communities. However, the main challenges encountered were bureaucratic procurement processes and weak distribution systems, which hindered timely implementation. These issues are beyond the control of on-the-ground practitioners and require resolution at a higher programmatic level.
Geographical Factor
Lastly, the study also explored how demographic, resource, and geographical factors impact the completeness and coverage of mass dog vaccination (MDV) campaigns. It found that vaccination units with more dogs, often in pastoralist communities, had lower coverage, likely because these communities, which rely on livestock, face challenges in bringing dogs to central vaccination points. Rural areas, with larger vaccination units and more dogs, also struggled with coverage. Interestingly, campaigns conducted during the dry season had lower completeness and coverage than those in the wet season, possibly due to farmers’ preparatory activities and pastoralists’ movements. The study suggests that campaign planning should consider agricultural cycles and pastoralist movements to improve outcomes.
Miscellaneous
Data From Study:
Rabies / Vaccination Campaigns / Southeastern Tanzania
Year of Publication:
2022
External Link:
Sambo M, Ferguson EA, Abela-Ridder B, Changalucha J, Cleaveland S, Lushasi K, et al. (2022) Scaling-up the delivery of dog vaccination campaigns against rabies in Tanzania. PLoS Negl Trop Dis 16(2): e0010124.
https://doi.org/10.1371/journal.pntd.0010124