This document aims to help EU/EEA public health authorities in the tracing and management of persons, including healthcare workers, who had contact with COVID-19 cases. It outlines the key steps of contact tracing, including contact identification, listing and follow-up, in the context of the COVID-19 response.
This document outlines the key steps of contact tracing, including contact identification, listing and follow-up, in the context of the COVID-19 response.
Contact management is based on the latest available evidence, as outlined below.
• Current estimates suggest a median incubation period from five to six days, with a range from 1 to 14 days. A recent modelling study confirmed that it remains prudent to consider an incubation period of up to 14 days [1,2].
• A case may already be infectious up to 48 hours before the onset of symptoms. A recent study reported that 12.6% of case reports indicated presymptomatic transmission . In addition, the proportion of presymptomatic transmission has been inferred through modelling and was estimated to be – in the presence of control measures – at around 48% and 62% in Singapore and China (Tianjin data), respectively . Other studies have shown no significant difference in viral load in asymptomatic and symptomatic patients, indicating the potential of virus transmission from asymptomatic patients [5-7].
• Transmission is believed to be mainly via respiratory droplets and direct contact with infected people and indirect contact with surfaces or objects in the immediate environment . Recent experimental studies carried out under highly controlled conditions have demonstrated the survival of SARS-CoV-2 on different surfaces and in aerosol. Different levels of environmental contamination have been described in rooms of COVID-19 patients [9-11].
• Up to 10% of reported cases in China  and up to 9% of cases in Italy were among healthcare workers . It is likely that nosocomial outbreaks play an important role in amplifying local outbreaks, and they disproportionately affect the elderly and vulnerable populations.