Abstract
The ongoing investigations into clusters of children affected by severe acute hepatitis of unknown aetiology have put our global capacity for a coordinated, effective response to the test. The global health community have rapidly convened to share data and inform the response. In the UK, where most cases were initially identified, a coordinated public health and clinical research response was rapidly initiated. Since then, cases have been reported from other countries, predominantly from higher-income countries. While agencies are keeping an open mind to the cause, the working hypothesis and case notifications raise important questions about our capacity to detect emerging cases in lower-resourced settings with a recognised lack of access to diagnostics even for commonly circulating viruses such as hepatitis A. The limited capability to generate integrated global pathogen surveillance data is a challenge for the outbreak investigations, highlighting an urgent need to strengthen access to diagnostics, with a focus on lower-resourced settings, to improve the capacity to detect emerging diseases to inform care and to improve outcomes and outbreak control.