Developing a Core Outcome Set for COVID-19 prevention interventions: the COS COVID-P study

Introduction/background
Interventions that minimise the spread of SARS-CoV-2 are essential to reduce COVID-19 morbidity and mortality. Various methods are being implemented worldwide, including vaccines and drugs for prophylaxis (Figure 1). Public health safety interventions such as social distancing, school closure and behavioural interventions such as hand washing and use of personal protective equipment (PPE), are increasing all the time. Research into the effectiveness of these interventions is accumulating, but evidence synthesis on the prevention of COVID-19 is unnecessarily difficult because of inconsistencies in how outcomes are measured(1-3). The recent rapid update of the Cochrane review of PPE highlights this, with the authors concluding that consensus around outcome assessment is urgently needed(1).
One solution would be a core outcome set (COS), an agreed standardised set of outcomes that would be measured and reported, as a minimum, in all studies of interventions to prevent SARS-CoV-2 infection(4). COS focusing on treatment of patients with COVID-19 are available(5-8) and a ‘meta-COS’ for hospitalised adult patients with confirmed or suspected COVID-19 has been agreed with two domains: mortality and respiratory support(9, 10). A COS for COVID-19 prevention interventions is overdue.
The COS COVID-P study aims to fill this gap, with a COS that will include a minimum set of outcomes for prevention studies worldwide(4). This may involve identification of core outcome domains relevant to all types of COVID-19 prevention interventions, and/or modules for specific interventions or settings. Widespread implementation of the COS will improve the quality and consistency of study reporting, enhancing the value of evidence synthesis, facilitating application of findings and reducing waste.