Rapid diagnostic test: a critical need for outbreak preparedness and response for high priority pathogens.

Rapid diagnostic tests (RDTs) are critical for preparedness and response against an outbreak or pandemic and have been highlighted in the 100 Days Mission, a global initiative that aims to prepare the world for the next epidemic/pandemic by driving the development of diagnostics, vaccines and therapeutics within 100 days of recognition of a novel Disease X threat.RDTs play a pivotal role in early case identification, surveillance and case management, and are critical for initiating deployment of vaccine and monoclonal antibodies. Currently available RDTs, however, have limited clinical sensitivity and specificity and inadequate validation. The development, validation and implementation of RDTs require adequate and sustained financing from both public and private sources. While the World Health Assembly recently passed a resolution on diagnostic capacity strengthening that urges individual Member States to commit resources towards this, the resolution is not binding and implementation will likely be impeded by limited financial resources and other competing priorities, particularly in low-income countries. Meanwhile, the diagnostic industry has not sufficiently invested in RDT development for high priority pathogens.Currently, vaccine development projects are getting the largest funding support among medical countermeasures. Yet vaccines are insufficient tools in isolation, and pandemic preparedness will be incomplete without parallel investment in diagnostics and therapeutics.The Pandemic Fund, a global financing mechanism recently established for strengthening pandemic prevention, preparedness and response, may be a future avenue for supporting diagnostic development.In this paper, we discuss why RDTs are critical for preparedness and response. We also discuss RDT investment challenges and reflect on the way forward.