The global Eliminate Yellow fever Epidemics (EYE) strategy is committed to strengthening surveillance and diagnostic capacity in countries and regions. A limitation to detecting yellow fever outbreaks has been the complexity of the diagnostics. EYE and partners have been working with the Foundation for Innovative New Diagnostics (FIND) to improve diagnostics for yellow fever. The development of target product profiles (TPPs) is intended to catalyze the development of new and improved options to diagnosis yellow fever.
The TPP development process was conducted by FIND in partnership with Gavi and WHO for three diagnostic tools: (i) molecular, (ii) serologic, and (iii) rapid diagnostic testing. Currently available assays are for research use only and as a result testing, reagents and quality measures are not standardized across laboratories and tests. However, there are no commercially available, fully validated diagnostic kits for molecular or serological detection of yellow fever infection. The purpose of the TPPs is to inform product developers of key characteristics and performance specifications required to meet the laboratory’s needs for detecting yellow fever infections to inform development of improved diagnostics. The yellow fever diagnostic TPPs include an optimal and minimal definition for each performance characteristic. Ideally, products should be designed to achieve as many of the optimal characteristics as are feasible, while still satisfying the minimal criteria for all defined features. These three TPPs will guide assessments of which yellow fever diagnostic tests perform well enough to warrant use in the laboratory network and facilitate outreach to manufacturers to encourage them to develop test kits that demonstrate the specified level of performance.
Improved standardized diagnostic options with established performance and validation can help reduce the time to confirm outbreaks. With faster detection, there can be rapid response to control outbreaks earlier and close to source. Currently only national and regional reference labs have the diagnostic capacity to confirm yellow fever. Development of TPPs is one element towards increased capacity to confirm outbreaks. These improvements in diagnostics are envisioned to support testing both at the national and regional reference labs and to further decentralized testing.
Currently, the Global Yellow Fever Laboratory Network in Africa coordinated by WHO relies on serologic testing of IgM antibodies and on detection of yellow fever virus RNA in the blood from acute cases of yellow fever using laboratory protocols. With new diagnostic methods on the market, particularly the development of a rapid diagnostic test, could extend yellow fever diagnostics beyond Regional and National Reference laboratories to have increased availability and impact in peripheral and field levels of the health system. Coupled with strong surveillance, these new diagnostics will help ensure easier, faster and more accurate diagnosis of yellow fever virus.
In addition, the EYE Strategy is supporting the expansion of laboratory capacity particularly in yellow fever high risk countries in Africa. The regional reference laboratory Institut Pasteur de Dakar has been joined by the Uganda Virus Research Institute which supports Eastern and Southern Africa region, and the network is anticipated to grow with the nomination of Centre Pasteur de Cameroon for the Central Africa region. This expansion is another element expected to help improve the speed of case confirmation in endemic countries, which is key to ensure timely outbreak response measures, including vaccination campaigns.
For further information on how to contribute, please contact us at EYE.strategy@who.int