Latest risk assessment: current SARS-CoV-2 epidemiological situation in the EU/EEA, projections for the end-of-year festive season and strategies for response, 24 November 2021
Increases in case notifications, hospitalisations and intensive care unit (ICU) admissions for SARS-CoV-2 have been observed in October and early November in the majority of EU/EEA countries, after a period of decline in August and September 2021. This has been driven by circulation of the Delta variant (B.1.617.2) in the context of insufficient vaccine uptake and widespread relaxation of non-pharmaceutical interventions (NPIs). Whilst the burden from COVID-19 is particularly high in a number of countries experiencing low vaccine uptake, there is evidence of rising burden even among countries with higher uptake. The current epidemiological situation is to a large part driven by the high transmissibility of the Delta variant that counteracts the reduction in transmission achieved by the current vaccination rollout in the EU/EEA.
To date, 65.4% of the total population and 76.5% of the adult population in the EU/EEA have been fully vaccinated against COVID-19. The overall pace of weekly increase in vaccine uptake in the EU/EEA is slowing down and is mostly driven by the rollout in younger age groups. Four countries are still reporting less than 50% of full vaccine uptake in the total population. Vaccination continues to successfully avert deaths, reduce hospitalisations and transmission in the EU/EEA, despite the emergence and continued dominance of the Delta variant, which is up to 60% more transmissible than the previously dominant variant, Alpha (B.1.1.7).
Available evidence emerging from Israel and the UK shows a significant increase in protection against infection and severe disease following a booster dose in all age groups in the short term. All EU/EEA countries have begun administration of ‘additional dose’ vaccination (to better protect individuals who mount inadequate immune responses to the primary schedule) and ‘booster’ vaccinations (to improve protection in individuals for whom immunity may wane over time since completing the primary schedule).
The end-of-year festive season is traditionally associated with activities such as social gatherings, shopping and travelling, which pose significant additional risks for intensified transmission of Delta.
Modelling scenarios that consider vaccine uptake (including ‘additional dose’ and ‘booster’ vaccinations), vaccine effectiveness, waning vaccine-induced immunity, vaccination of children, natural immunity and population contact rates, indicate that the potential burden of disease risk in the EU/EEA from the Delta variant is expected to be very high in December and January, unless NPIs are applied now in combination with continued efforts to increase vaccine uptake in the total population.
Modelling forecasts highlight the need for NPIs as an immediate measure to control transmission, in combination with rollout of vaccine booster doses for adults, which should be prioritised for those aged 40 years and over, at least six months after completing a primary vaccine schedule. Booster doses will sustain transmission control beyond the immediate impact of implementing NPIs.
Risk assessed in this update
Based on current vaccination coverage and the circulation of the Delta variant in the EU/EEA, what risk does SARSCoV-2 pose to the general and vulnerable population?
We assess the risk to broad groupings of EU/EEA countries based on their current and projected levels of vaccination coverage for the total population. Through mathematical modelling, we forecast the disease burden (hospitalisations and deaths) between 1 December 2021 and 31 January 2022. The assessment of risk posed by the SARS-CoV-2 pandemic is further stratified for the following groups in the total population: the vaccinated and the unvaccinated general population; the vaccinated and the unvaccinated vulnerable population. The assessment is based on the following elements: i) the vaccinated have a lower probability of infection and ii) a lower impact of such infection than the unvaccinated, while iii) the vulnerable population suffers a higher impact if infection occurs, when compared with the general population. Based on modelling projections, virus circulation and disease burden between 1 December 2021 and 31 January 2022, the following can be anticipated:
- In order to avoid a high COVID-19 burden, countries with a low (<60%) or average (60-80%) vaccine
uptake for the total population will require substantial reductions in contacts between people to avoid a high
burden from SARS-CoV-2 transmission. For countries that are currently experiencing high COVID-19 burden,
high contact reductions can achieve a manageable burden towards the end of the December-January
- Countries with higher (>80%) vaccine uptake for the total population could experience a manageable burden at current contact rates. However, this burden could become high if contact rates increase further, as might be expected given the end-of-year festive season.
- Because vaccines offer high protection against severe outcomes of COVID-19 infection, a large number of COVID-19 hospital admissions will be unvaccinated individuals, in particular unvaccinated individuals in risk groups. However, since vaccine effectiveness against severe disease is not 100%, increased notification rates will also lead to an increased number of vaccinated individuals experiencing severe forms of disease requiring hospitalisation. Together with waning immunity over time from vaccination, this explains the proportion of vaccinated individuals among hospitalised COVID-19 patients in some countries with high vaccine uptake.
Options for response
The current average level of vaccine uptake in the EU/EEA will be insufficient to limit the burden of COVID-19 cases and hospitalisations over the winter months.
Countries are urged to give utmost priority to individuals initially targeted by COVID-19 vaccination programmes that remain unvaccinated or not yet fully vaccinated. Increasing COVID-19 vaccination coverage in all eligible age groups, but particularly in the elderly, in the vulnerable, and in healthcare workers should remain the priority for public health authorities. There remains an urgent need to close immunity gaps in the adult population and ensure effective and equitable coverage across countries and regions in Europe.
National Immunisation Technical Advisory Groups (NITAGs) in EU/EEA countries should consider a booster dose for those 40 years and over, targeting the most vulnerable and the elderly. Countries could also consider a booster dose for all adults 18 years and older at least six months after completion of the primary series to increase protection against infection due to waning immunity, which could potentially reduce transmission in the population and prevent additional hospitalisations and death.
Given that pressures to healthcare systems may arise due to co-circulation of other respiratory viruses, NPIs should be implemented or reinforced now, with efforts to communicate the importance of these measures early, to reduce contacts and mixing during the end-of-year festive season.
At this stage, even in countries with high vaccine uptake, maintaining or reintroducing NPIs remains vital to reduce transmission. Timely implementation of NPIs is critical for their success. Appropriate use of face masks, teleworking and operational modifications that reduce crowding on public transport, along with ensuring adequate ventilation in closed spaces and maintenance of hygiene measures that can be implemented immediately. Setting limits for the number of participants in social and public events during endof-year celebrations will support physical distancing efforts. Once implemented, countries should anticipate that NPIs may need to be retained for a prolonged period of time after the festive/holiday period, at levels that adequately complement vaccination protection, in order to effectively control virus circulation.
Risk communication activities should emphasise the continued importance of hygiene measures and avoidance of unnecessary crowding to the control of virus circulation, particularly as countries work towards increasing vaccine uptake. Messaging should also stress the importance both COVID-19 and influenza vaccines play in protecting people against severe forms of disease.
Given the continued risk of transmission amongst children, high levels of prevention and preparedness are required in the educational system.
Testing, contact tracing, and monitoring and reporting of COVID-19 cases, hospitalisations, deaths and vaccine effectiveness remain vital to guide decisions on public health measures and to understand their impact. In light of the co-circulation of other respiratory viruses (e.g. influenza and respiratory syncytial virus (RSV)), multiplex assays should be considered for testing of several respiratory pathogens simultaneously.
Genomic sequencing of positive samples remains of high importance to characterise currently circulating variants, and to detect the emergence of novel variants with concerning characteristics.
Updated assessment on all variants of concern
SARS-CoV-2 variants of concern as of 3 December 2021
ECDC regularly assesses new evidence on variants detected through epidemic intelligence, rules-based genomic variant screening or other scientific sources.