Diagnostics are an essential part of a well functioning and high-quality health system. Yet, almost half of the global population has little or no access to diagnostics. The COVID-19 pandemic has shown acutely that diagnostic capacity in a country is directly linked to the ability to respond to the pandemic with appropriate public health measures and to monitor emerging variants. There is an urgent need to strengthen diagnostics for future pandemic preparedness but also beyond pandemics. Diagnostics are central to an accurate diagnosis of communicable and non-communicable diseases, to guide therapy, monitor progress, and assess response to treatment. The Commission puts forward recommendations to accelerate and transform access to diagnostics globally.