Baseline situation for the scenarios
As at 1 March, 87,024 cases and 2,979 associated deaths have been reported worldwide [1]. The vast majority of the deaths (96%) have been reported in China [1]. Despite the high number of cases reported globally, estimates of the severity pyramid of disease and case fatality rate remain very uncertain; one large study conducted in China estimated that the majority (81%) of the cases were mild (i.e. non-pneumonia or mild pneumonia), 14% were severe (e.g. with dyspnoea) and 5% were in a critical condition (i.e. respiratory failure, septic shock and/or multiple organ dysfunction/failure) [2]. The case fatality ratio was 2.3% [2].
Despite extraordinary containment measures implemented in China, including the enforced lockdown of several cities and closures of schools, the virus has spread throughout the country and internationally [2]. It is too early to predict with any certainty the epidemiological developments over the coming weeks, but the possibility of widespread community transmission becoming established throughout the EU/EEA is becoming increasingly likely.
We performed a strengths, weaknesses, opportunities and threats (SWOT) analysis (Box), which guided the development of scenarios for the potential progression of the epidemic in the EU/EEA. For this SWOT analysis, points that were directly linked to the EU/EEA were classified as strengths or weaknesses; points that were not directly linked to the EU/EEA but (potentially) affecting the EU/EEA were categorised as opportunities or threats.
Box  Strengths, weaknesses, opportunities and threats in relation to COVID-19, EU/EEA, 2020
Strengths
Low incidence rates of COVID-19 in the EU/EEA region outside the most affected areas allow time to learn about epidemiology and the effectiveness of control measures from the global experience.
Response efforts are coordinated at the EU/EEA level, enabling harmonisation of surveillance and epidemiological assessment.
Information about cases within the EU/EEA can be gathered and exchanged rapidly and securely using tools such as the Early Warning and Response System (EWRS) and The European Surveillance System (TESSy).
All EU/EEA countries evaluate that they have the laboratory capacity to detect cases [6].
Under scenario 1 and 2 (see below), EU/EEA countries are expected to have the hospital capacity and human resources required to isolate and care for cases and to conduct contact tracing.
Well-functioning influenza surveillance systems in the EU/EEA can rapidly be adapted to detect SARS-CoV-2 infections of differing severity.
All EU/EEA countries have pandemic preparedness plans that could be adapted and activated should the epidemiological situation deteriorate.
Weaknesses
Large uncertainty remains regarding the severity of disease, case fatality ratios and risk groups.
Mild and asymptomatic cases are likely to be undetected [7] but may contribute to transmission [8].
Pressure on healthcare systems because of seasonal influenza may reduce the surge capacity needed to cope with the additional demand from COVID-19 cases in the EU/EEA.
Entry screening is not effective because the majority of cases would be in the incubation period and therefore undetected.
Supply chains for personal protective equipment and medicines may not be resilient to the disruption of a global outbreak.
The capacity to isolate cases can be stretched only to a certain extent.
The transmission potential of SARS-CoV-2 through substances of human origin remains unknown.
Concentrated transmission during mass gathering events in the EU/EEA would hamper containment efforts.
Co-occurrence with an outbreak of, for example, West Nile fever or chikungunya virus infection would add pressure on public health authorities. Similarly, ongoing prevention programmes (e.g. measles vaccination campaigns) may be affected.
Opportunities
Considerable containment efforts in China in January and February appear to have limited transmission and therefore exportation.
Global surveillance and communication efforts improve knowledge about the virus, the disease and transmission patterns.
If SARS-CoV-2 demonstrates seasonality like influenza and other respiratory tract viruses, a decline in cases during summer would provide time to prepare for the following transmission season.
Threats
It is uncertain how long the authorities in the most affected countries will be able to sustain the present containment measures.
Large outbreaks now taking place outside of China increase the rate of importation into and within the EU/EEA, challenging the containment strategy currently in place.
Some countries are reporting fewer importations than would be inferred from travel volumes, suggesting that circulation of the virus is more widespread than it appears from case detection and a pandemic may occur sooner than expected [9].
Globalisation of trade and frequent international travel will facilitate the spread of the virus.
Vaccines and antiviral treatments are under development but may not be widely available for several months or even years.
The outbreak could cause substantial social, political and economic disruption also in parts of the world not directly affected by the virus.
COVID-19: coronavirus disease 2019; EU/EEA: European Union/European Economic Area; SARS-CoV-2: severe acute respiratory syndrome-related coronavirus 2.