The World Health Organisation (WHO) has warned that the new Omicron variant of the coronavirus will likely outpace the Delta variant, based on limited preliminary data.
The WHO said the strain, titled B.1.1.529 and classified as a variant of concern at the end of November, may be associated with "immune escape potential and higher transmissibility." But the organisation added that there are still considerable uncertainties surrounding the variant.
It stressed that the overall threat posed by Omicron largely depends on how transmissible it is, how effective vaccines are against it, and how virulent the variant is compared to others.
"Given the available data, it is likely that Omicron will outpace the Delta variant where community transmission occurs," the WHO stated.
Citing the limited data, it seems that the new strain spreads faster than the Delta variant. This is true both in countries where the circulation of the current dominant strain was low, such as South Africa, as well as where the incidence of Delta is high, such as in the United Kingdom.
It stressed that the strain also seems to be slightly more resistant to vaccines. Although no peer-reviewed research on the efficacy and effectiveness of vaccines against the variant has yet been published, recent research shows that it partly escapes the protection offered by the Pfizer-BioNTech vaccine. However, three doses of that same vaccine does neutralise the strain.
Need for more data
Data on the severity of the symptoms of an Omicron infection is also limited but preliminary findings from South Africa suggest that it may be less severe than those experienced by people with infections linked to the Delta variant.
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According to the latest data from the European Centre for Disease Control and Prevention (ECDC) indicates a less severe illness: most of those infected were either asymptomatic or presented only mild symptoms. There have so far been no Omicron-related deaths in Europe.
The WHO stressed the need for more data is needed to understand the severity profile of the Omicron variant. It added that the current understanding is likely to evolve as more data becomes available.
As of 9 December, the Omicron variant – which has the highest number of mutations seen in any strain since the start of the coronavirus pandemic – has been linked to cases in more than 63 countries across the world.