The need to improve access to rabies post-exposure vaccines: Lessons from Tanzania

Abstract

Background: Rabies is preventable through prompt administration of post-exposure prophylaxis (PEP) to exposed persons, but PEP access is limited in many rabies-endemic countries. We investigated how access to PEP can be improved to better prevent human rabies.

Methods: Using data from different settings in Tanzania, including contact tracing (2,367 probable rabies exposures identified) and large-scale mobile phone-based surveillance (24,999 patient records), we estimated the incidence of rabies exposures and bite-injuries, and examined health seeking and health outcomes in relation to PEP access. We used surveys and qualitative interviews with stakeholders within the health system to further characterise PEP supply and triangulate these findings.

Results: Incidence of bite-injury patients was related to dog population sizes, with higher incidence in districts with lower human:dog ratios and urban centres. A substantial percentage (25%) of probable rabies exposures did not seek care due to costs and limited appreciation of risk. Upon seeking care a further 15% of probable rabies exposed persons did not obtain PEP due to shortages, cost barriers or misadvice. Of those that initiated PEP, 46% did not complete the course. If no PEP was administered, the risk of developing rabies following a probable rabies exposure was high (0.165), with bites to the head carrying most risk. Decentralized and free PEP increased the probability that patients received PEP and reduced delays in initiating PEP. No major difficulties were encountered by health workers whilst switching to dose-sparing ID administration of PEP. Health infrastructure also includes sufficient cold chain capacity to support improved PEP provision. However, high costs to governments and patients currently limits the supply chain and PEP access. The cost barrier was exacerbated by decentralization of budgets, with priority given to purchase of cheaper medicines for other conditions. Reactive procurement resulted in limited and unresponsive PEP supply, increasing costs and risks to bite victims.

Conclusion: PEP access could be improved and rabies deaths reduced through ring-fenced procurement, switching to dose-sparing ID regimens and free provision of PEP.

Keywords: Canine rabies; Dog-mediated rabies; Immunoglobulin; Intradermal; Intramuscular; Post-exposure prophylaxis; Procurement; Rabies prevention; Supply chain; Vaccine regimen.

Fig. 1

Variation in the annual incidence of patients presenting to clinics across Tanzania with bite injuries. Points are ordered by the estimated human:dog ratio for each district, and districts are coloured according to whether they are urban or rural. Data from twenty-eight districts in Southern Tanzania (2011–2016) are shown together with data from Serengeti and Ngorongoro (2003–2006, prior to routine annual dog vaccination campaigns). Black points show the average annual incidence, coloured points show annual data and the box and whiskers show the range and interquartile range.

Fig. 2

Initiation and completion of post-exposure vaccination according to access: (A) delay between date bitten and first post-exposure vaccination for individuals bitten by probable rabid animals and (B) proportion of patients that received 1–5 doses of PEP. Blue indicates locations where patients were required to pay for PEP (Serengeti and Ngorongoro) and yellow indicates locations where PEP was provided for free (28 districts in Southern Tanzania). Panel A shows contact tracing data on delays between exposure and initiation of PEP for rabies exposed persons (781 exposures from Serengeti and Ngorongoro districts, and 607 exposures from 11 districts in southern Tanzania). Out of 794 patients identified through contact tracing who had delayed PEP (more than 1 day late), nine deaths occurred (Table 2). Panel B shows mobile phone-based surveillance records from Southern Tanzania (yellow, n = 21,692) of PEP completion and contact tracing data on rabies exposed patients from Serengeti and Ngorongoro districts (n = 1,200). Not all bite victims received the first PEP dose because of shortages at the facility or costs required to purchase PEP. Rabies exposed persons who did not seek care (identified through contact tracing) are not shown. In Serengeti district patients were typically vaccinated following a 3 dose IM regimen (d0, d7, d28) and in Ngorongoro district following the 5-dose Essen IM regimen (d0, d3, d7, d14, d28). In southern Tanzania, most patients were vaccinated following the updated Thai Red Cross ID regimen (d0, d3, d7, d28).

Fig. 3

Schematic of the number of visits to health facilities made by patients to obtain PEP within their district, in other district in their region, and in other regions. All clinic visits were from patients located within the study districts. The schematic also shows the proportion of visits made to multiple facilities and their locations.