Epidemiological update: Omicron variant of concern (VOC) – data as of 15 December 2021 (12:00)

According to information from public sources, confirmed cases have been reported by 27 EU/EEA countries: Austria (59), Belgium (90), Croatia (3), Cyprus (3), Czechia (9), Denmark (310*), Estonia (6**), Finland (20), France (170), Germany (102), Greece (5), Hungary (2), Iceland (20), Ireland (18), Italy (27), Latvia (14), Liechtenstein (1), Lithuania (2), Luxembourg (1), the Netherlands (80), Norway (1 498***), Portugal (69), Romania (11), Slovakia (3), Slovenia (4), Spain (51) and Sweden (51). Two new countries (Lithuania and Slovenia) have reported cases since yesterday and several countries have reported a number of probable cases.

Although cases reported initially were linked to travel, an increasing number of cases are now being reported as acquired within the EU/EEA, including as parts of clusters and outbreaks, with cases also being detected in representative 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 13% (22) cases, while 70% (121) of the cases reported to TESSy were acquired locally, including 45% (78) cases sampled as part of local outbreak investigations.

EU/EEA countries reporting cases without an epidemiological link to travel include Belgium, Denmark, Finland, Hungary, Norway, Netherlands, Portugal, Spain, Sweden and Iceland. This indicates that undetected community transmission could be ongoing in the EU/EEA.

All cases in the EU/EEA for which there is available information on severity were either asymptomatic or mild. Within the EU/EEA there have been no Omicron-related deaths reported so far. However, these data should be assessed with caution, as the number of confirmed cases is too low to understand whether the disease clinical spectrum of Omicron differs from that of previously detected variants.

Countries and territories outside of the EU/EEA have reported 7 521 confirmed cases. The 53 countries and territories reporting confirmed cases are: Argentina, Australia, Bahrain, Bangladesh, Bermuda (UK), Botswana, Brazil, Cambodia, Canada, Chile, China, Cuba, Fiji, Ghana, Gibraltar (UK), India, Israel, Japan, Jordan, Kuwait, Lebanon, Malawi, Malaysia, Maldives, Mauritius, Mexico, Namibia, Nepal, Nigeria, Oman, Pakistan, Philippines, Russia, Rwanda, Saudi Arabia, Senegal, Sierra Leone, Singapore, South Africa, South Korea, Sri Lanka, Switzerland, Taiwan, Thailand, Trinidad and Tobago, Tunisia, Turkey, Uganda, United Arab Emirates, United Kingdom, United States of America, Zambia and Zimbabwe.

On 13 December 2021, the UK Health Security Agency reported one Omicron-related death. This individual was diagnosed in hospital.

Overall, there were 10 150 confirmed cases globally, reported by 80 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 compared to Delta VOC infection in individuals that received two vaccine doses. However, vaccine effectiveness against Omicron infection was similar to that for 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 15 December 2021 (12:00)

* Denmark reported 310 cases as confirmed through whole genome sequencing and 4 225 as confirmed nationally through a variant-specific PCR.

** There are less cases reported today for Estonia than previously. This is because probable cases had been erroneously included.

*** Norway announced that probable cases of Omicron VOC infection 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 a confirmed sequencing result for the SARS-CoV-2 Omicron VOC.