RAPID RISK ASSESSMENT Coronavirus disease 2019 (COVID-19) in the EU/EEA and the UK – tenth update, 11 June 2020
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5. Limitations
This assessment is undertaken based on information available to ECDC at the time of publication.
There is still limited epidemiological and clinical information on COVID-19 (e.g. efficiency of different modes of
transmission, proportion of mild and asymptomatic cases, transmission during incubation and recovery period,
effectiveness of treatment regimes, risk factors for severe illness other than age and effective preventive measures).
There are several challenges to assessing the effectiveness of physical distancing measures. It is important to keep
in mind that pre/post ‘stay-at-home’ order comparisons cannot take into account many of the factors that may
have influenced disease occurrence, severity, deaths and trend, in recent weeks and months. For instance, if
patient management improved over time (including management of patients during early stages of the disease in
the community), this could influence trends in hospitalisation, severity and deaths due to COVID-19. In addition,
potential concomitant changes in the pathogenicity of COVID-19, for which there is no evidence as yet, would not
be accounted for and therefore these would be attributed to the effect of the ‘stay-at-home’ measures. Finally, the
type of ‘stay-at-home’ measures and compliance with them may vary by country, and by region within each
country, and over time making it difficult to assess its overall impact.
It is also important to consider that the lag-time between infection, symptoms, diagnosis, disease notification,
death, and death notification should be factored into the analysis, and may be subject to several biases including
changes in testing and reporting over time. This means that the effects of introducing any measure will not be
seen until weeks after its full implementation, and its impact will continue to be observed for weeks after the
measure will have been lifted.
If assessing the impact of ‘stay-at-home’ measures had potential challenges, assessing the impact of specific measures
could be even more complex. These measures are in fact being lifted in the context of a general societal re-opening that
is taking place in a variety of forms across Member States (and across regions within each Member State) for a number
of different reasons. The factors for consideration include number of, type of, and compliance with other measures still in
place; changes in individual behaviour related to physical distancing; differences and changes in population immunity;
cultural and societal aspects; regional differences; and changes in testing and reporting.
Since SARS-CoV-2 is a novel pathogen, many features of its transmission and infection dynamics are not yet well
characterised. Therefore, the uncertainties of published results and the outcome of modelling exercises should be
taken into account when interpreting these findings.
Given these limitations, ECDC will revise the current risk assessment as soon as more information becomes available.
6. Source and date of request
ECDC internal decision, 28 May 2020.
7. Consulted experts
ECDC experts (in alphabetical order): Cornelia Adlhoch, Barbara Albiger, Leonidas Alexakis, Agoritsa Baka, Julien
Beauté, Eeva Broberg, Sergio Brusin, Nick Bundle, Orlando Cenciarelli, Bruno Ciancio, Edoardo Colzani, Stefania De
Angelis, Sebastian Deka, Tarik Derrough, Dragoslav Domanovic, Erika Duffell, Lisa Ferland, Emilie Finch, Lea
Franconeri, Tjede Funk, Joana Gomes Dias, Céline Gossner, Helen Johnson, Pete Kinross, John Kinsman, Csaba
Tommi Kärki, Ködmön, Katrin Leitmeyer, Felix Lotsch, Irina Ljungqvist, Giovanni Mancarella, Angeliki Melidou,
Grazina Mirinaviciute, Thomas Mollet, Lina Nerlander, Taina Niskanen, Teymur Noori, Daniel Palm, Pasi Penttinen,
Anastasia Pharris, Diamantis Plachouras, Emmanuel Robesyn, Andreea Salajan, Emily Scott, Jan Semenza, Ettore
Severi, Helena Simanova, Bertrand Sudre, Carl Suetens, Jonathan Suk, Lars Söderblom, Svetla Tsolova, Klaus
Weist, Ivo Van Walle, Ariana Wijermans, Emma Wiltshire, Andrea Würz.
Disclaimer
ECDC issues this risk assessment document based on an internal decision and in accordance with Article 10 of
Decision No 1082/13/EC and Article 7(1) of Regulation (EC) No 851/2004 establishing a European centre for
disease prevention and control (ECDC). In the framework of ECDC’s mandate, the specific purpose of an ECDC risk
assessment is to present different options on a certain matter. The responsibility on the choice of which option to
pursue and which actions to take, including the adoption of mandatory rules or guidelines, lies exclusively with the
EU/EEA Member States. In its activities, ECDC strives to ensure its independence, high scientific quality,
transparency and efficiency.
This report was written with the coordination and assistance of an Internal Response Team at the European Centre
for Disease Prevention and Control. All data published in this risk assessment are correct to the best of our
knowledge at the time of publication. Maps and figures published do not represent a statement on the part of
ECDC or its partners on the legal or border status of the countries and territories shown.