The overall risk related to Omicron, the new variant of concern (VOC) of novel coronavirus SARS-CoV-2, remains very high due to multiple reasons, the World Health Organization (WHO) warned in its latest technical brief December 10, 2021.
Preliminary evidence suggests potential immune escape against infection and high transmission rates, which could lead to further surges with severe consequences, it said. The understanding, however, is still evolving, it added.
The variant could become the dominant variant in Europe within the next few months, the European Centre for Disease Prevention and Control flagged. A-1.5 times higher transmission compared to Delta could result in the Omicron variant being dominant by March 2022, assuming the proportion of Omicron variant circulating in Europe in December was at 0.1 per cent, the WHO brief stated.
More countries across all six WHO regions reported confirmed cases of the Omicron variant since December 7, 2021, when the WHO released its last update. As of December 9, the variant had been confirmed in 63 countries.
Community transmission has been confirmed in South Africa and the United Kingdom and cases with no epidemiological link to travel outside the European Union or European Economic Area have been reported in Belgium, Denmark, Finland, Spain and Iceland, the latest update stated.
More data and time would be needed to assess the clinical severity from the variant, as data on hospitalisation remained limited, the brief flagged.
It added: “While South Africa reported an 82 per cent increase in hospital admissions due to COVID-19 (from 502 to 912) between November 28 and December 4, 2021, the proportion of those hospitalisations that are due to the Omicron variant, compared to the proportion of community transmission due to Omicron, is not yet known.”
On immunity evasion, the release cited results from four non-peer-reviewed studies of the effect of neutralising antibodies on sera from naturally infected and vaccinated individuals. All studies showed significant reductions in neutralisation against Omicron by different sets of plasma samples when compared to the ancestral strain and other VOCs.
The released, however, added a word of caution: That these are preliminary findings based on low numbers of samples, and further evidence from larger studies would be needed to arrive at a more robust conclusion.
It urged countries that have not yet detected Omicron to monitor its introduction through targeted sequencing of suspected Omicron cases and detect community transmission through enhanced random sampling among SARS-CoV-2 confirmed cases.
Omicron was labelled a VOC on November 26, 2021. Omicron appears to have a growth advantage over Delta, based on current data that is limited.
It spreads faster than the Delta variant in South Africa where Delta circulation was low but also appears to spread more quickly than the Delta variant in other countries where the incidence of Delta is high, such as in the United Kingdom, the release flagged.