WHO chief: Omicron may be less severe, but not 'mild'

Speaking at a media briefing, the director general, Tedros Adhanom Ghebreyesus, also repeated his call for greater equity globally in the distribution of and access to vaccines.

Based on the current rate of vaccine rollout, 109 countries will miss the WHO’s target for 70% of the world’s population to be fully vaccinated by July, Tedros added. That aim is seen as helping end the acute phase of the pandemic.

Another variant – labelled as IHU and first registered in September 2021 – is among those being monitored by the WHO but is not circulating widely, said the WHO’s technical lead on Covid-19, Dr Maria van Kerkhove.

There are two other categories of greater significance the WHO uses to track variants: "variant of concern", which includes Delta and Omicron, and "variant of interest".

Speaking at the same briefing from Geneva, the WHO adviser Bruce Aylward said 36 nations had not even reached 10% vaccination cover. Among severe patients worldwide, 80% were unvaccinated, he added.