ECDC publishes new risk assessment on further emergence of Omicron variant

News story

ECDC has published the eighteenth update of its rapid risk assessment (RRA). This RRA extends the assessment on the circulation of the Delta variant of concern (VOC) and projections for the festive period that was published on 24 November 2021, including the emergence and spread of the Omicron VOC. The inclusion of updated forecasts developed for this risk assessment are informed by the latest evidence on Omicron VOC epidemiology, transmissibility, severity, and immune escape.

Statement of ECDC Director Dr. Andrea Ammon

“Since I last addressed you, the emergence of the Omicron variant has raised serious concerns due to preliminary reports of clusters of cases, including among people who had been fully vaccinated. There are indications that community transmission is already ongoing in EU/EEA countries and based on modelling predictions a further rapid increase in Omicron cases is imminent. 

We assess the probability of further spread of the Omicron variant in the EU/EEA as very high, and it is considered very likely to cause additional hospitalisations and fatalities, further to those already expected from previous forecasts that consider only the Delta variant.

The effectiveness of vaccines against severe outcomes caused by Delta remains high, therefore vaccination remains a key component in reducing the impact of Omicron and addressing the circulation of Delta. According to surveillance data, nearly half a million lives have been saved by vaccines so far. Countries should ramp up efforts to increase full vaccination in people not yet vaccinated or only partially vaccinated, as well as to administer booster doses to all eligible as soon as possible. 

In the current situation, vaccination alone will not allow us to prevent the impact of the Omicron variant, because there will be no time to address the vaccination gaps that still exist. It is urgent that strong action is taken to reduce transmission and alleviate the heavy burden on health care systems and protect the most vulnerable in the coming months. Countries have several options for response ahead of the festive season in the current situation.

As we have said before, a rapid reintroduction and strengthening of non-pharmaceutical interventions is necessary to reduce the ongoing Delta transmission, slow down the spread of the Omicron variant of concern and keep the COVID-19-related burden manageable.

It remains a priority to use face masks appropriately, telework, prevent crowding in public spaces, reduce crowding on public transport, stay home when ill, maintain hand and respiratory hygiene measures and ensure adequate ventilation in closed spaces. Countries may expect a strong resurgence of cases if they lift these interventions.

For probable or confirmed cases of Omicron infection, contact tracing should be prioritised, regardless of vaccination status. Testing remains an important tool, and people with symptoms should be tested regardless of their vaccination status, together with isolation of positive persons, to limit the spread of the virus and to reduce the burden on healthcare systems. Genomic surveillance remains of high importance and genome sequencing should be performed to confirm infection with a specific variant.

These measures will not only help keep us healthy but will also protect those around us. By acting together, we can overcome the difficult situation that the pandemic has caused. As the festive season comes closer, we need solidarity more than ever before.”

Key messages in this RRA

  • Community transmission of Omicron VOC is already ongoing in EU/EEA countries (cases are detected through representative sampling within EU/EEA routine surveillance system) and further rapid increase in the Omicron VOC cases is expected in the next two months.
  • The Delta VOC remains currently the most prevalent variant. However, based on modelling predictions, and depending on the growth advantage and level of immune escape, the Omicron VOC is likely to become the dominant variant in the EU/EEA within the first two months of 2022.
  • Even if the severity of disease caused by the Omicron VOC is equal or lower than the severity of the Delta VOC, the increased transmissibility and resulting exponential growth of cases will rapidly outweigh any benefits of a potentially reduced severity. Therefore, the Omicron VOC is considered likely to cause additional hospitalizations and fatalities, further to those already expected from previous forecasts that consider only the Delta VOC.
  • The probability of further spread of the Omicron variant in the EU/EEA is VERY HIGH;
  • The overall level of risk to public health associated with the further emergence and spread of the SARS-CoV-2 Omicron VOC in the EU/EEA is assessed as VERY HIGH.
  • Rapid reintroduction and strengthening of NPIs is necessary to reduce the ongoing Delta transmission, slow down the spread of the Omicron VOC and keep the COVID-19-related burden manageable. It will slow the spread of the Omicron VOC, to allow countries to gain time for further vaccination roll-out and prevent a sudden high impact from the spread of this variant.
  • Vaccination remains a key component of the multi-layered approach needed in reducing the impact of Omicron, while also addressing the ongoing circulation of the Delta variant. Booster doses will increase protection against severe outcomes from the Delta VOC and possibly from Omicron.
  • Immediate planning for an increasing health care capacity to treat the expected higher number of cases should be considered. Risk communication activities emphasising the continued importance of being fully vaccinated and seeking an additional or booster vaccine dose, remain vital.
  • Reporting data to ECDC and monitoring vaccine effectiveness remains critical to address knowledge gaps in the context of the emerging Omicron VOC.