The COVID-19 outbreak is an emerging, rapidly evolving situation for which social distancing measures may be justified and implemented as a core component of the response. Public health authorities should ensure that decision makers are aware of, and understand, the current scientific uncertainties related to the virus [5]. These uncertainties include, among other issues:
• The precise mode(s) of transmission of the virus, and the possibility of aerosol transmission
• How long someone needs to be exposed in order to be infected
• Whether infectiousness starts before onset of symptoms, and how long a person is infectious
• Whether seasonality will affect transmission
• The role of children in transmission. Public health authorities should also recognise that extra-scientific factors (e.g. feasibility of implementing scientific advice, time pressure, socio-political factors, institutional factors, economic interests, pressure from neighbouring countries) are inherent to the decision-making process. These factors will also influence the implementation of any proposed response measures [1, 5]. Decisions should therefore always be evidence-informed, but they will very rarely be purely evidence-based.