Epidemiological update: Omicron variant of concern (VOC) – data as of 13 December 2021 (12:00)

Confirmed cases have been reported by 23 EU/EEA countries: Austria (17), Belgium (30), Croatia (3), Cyprus (3), Czechia (8), Denmark (195), Estonia (26), Finland (20), France (59), Germany (82), Greece (3), Iceland (20), Ireland (10), Italy (27), Latvia (5), Liechtenstein (1), the Netherlands (62), Norway (958), Portugal (49), Romania (8), Slovakia (3) Spain (36) and Sweden (23), according to information from public sources. In addition, a number of probable cases have been reported in several countries.

Although cases reported initially were linked to travel, an increasing number of cases are now reported to have been acquired within the EU/EEA, including as parts of clusters and outbreaks, with cases also being detected in representative sampling within routine surveillance systems.

A preliminary analysis of the initial Omicron VOC cases reported to The European Surveillance System (TESSy) shows that imported or travel-related cases account for 22 (13%) cases, while 121 (70%) of the cases reported to TESSy have been acquired locally, including 78 (45%) cases sampled as part of local outbreak investigations.

EU/EEA countries reporting cases without recent travel history/direct contact with travellers outside the EU/EEA include Belgium, Denmark, Finland, Spain and Iceland. This indicates that undetected community transmission could be ongoing in the EU/EEA.

All cases for which there is available information on severity were either asymptomatic or mild. There have been no Omicron-related deaths reported thus far. This data should be assessed with caution, as the number of confirmed cases is too low to understand if the disease clinical spectrum of Omicron differs from that of previously detected variants.

Countries and territories outside of the EU/EEA have reported 4 744 confirmed cases. The 47 countries reporting confirmed cases are: Argentina, Australia, Bahrain, Bangladesh, Bermuda (UK), Botswana, Brazil, Canada, Chile, Cuba, Hong Kong Special Administrative Region, Fiji, Ghana, Gibraltar, India, Israel, Japan, Jordan, Kuwait, Lebanon, Malawi, Malaysia, Maldives, Mauritius, Mexico, Namibia, Nepal, Nigeria, Russia, Saudi Arabia, Senegal, Sierra Leone, Singapore, South Africa, South Korea, Sri Lanka, Switzerland, Taiwan, Thailand, Tunisia, Turkey, Uganda, United Arab Emirates, United Kingdom, United States of America, Zambia and Zimbabwe.

Overall, there were 6 430 confirmed cases globally, reported by 70 countries.

A summary of available studies on the neutralising capacity of antibodies from convalescent or post-vaccination sera against the Omicron VOC virus is available in the epidemiological update from 10 December 2021.

The results of a vaccine effectiveness study conducted in the UK have been published as a pre-print (not yet peer-reviewed). The study shows a reduction of vaccine effectiveness against Omicron VOC infection as compared to Delta VOC infection in individuals that received two vaccine doses. However, vaccine effectiveness against Omicron infection was similar to that against Delta infection in individuals who had received an additional dose. The study did not assess vaccine effectiveness against severe outcomes. 

Table 1. Confirmed SARS-CoV-2 Omicron VOC cases reported by public sources, as of 13 December 2021 (12:00)

* Denmark reported 195 cases as confirmed through whole genome sequencing and 2 276 as confirmed nationally through a variant-specific PCR.

** Norway announced that probable cases of Omicron are now considered as confirmed cases and, therefore, the total number of Omicron detections included for Norway in this report consists of both probable and confirmed cases.

Case definitions

Probable case of SARS-CoV-2 Omicron VOC infection

A person with a positive nucleic acid amplification test (NAAT) or rapid antigen detection test (RADT) for SARS-CoV-2 AND one of the following: S-gene target failure or another PCR-based single nucleotide polymorphism (SNP) assay indicative of the SARS-CoV-2 Omicron VOC or is a contact of a probable or confirmed case of SARS-CoV-2 Omicron VOC infection.

Confirmed case of SARS-CoV-2 Omicron VOC infection

A person with confirmed sequencing result for the SARS-CoV-2 Omicron VOC.