Severe acute hepatitis of unknown aetiology in children—what is known?

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.