WHO officials remain cautious about claiming Omicron as a milder variant of the COVID-19 virus.

Vaccine manufacturers AstraZeneca and Novavax have said that their respective shots provide protection against the latest COVID-19 variant Omicron. This comes in the wake of UK data which has suggested that Omicron causes fewer hospitalisations than the Delta variant.

Novavax Inc has said that early data showed its vaccine – authorised for use this week by EU regulators and the World Health Organization (WHO), but yet to be approved in the US – generated an immune response against Omicron.

The same day, AstraZeneca announced that a three-course dose of its COVID-19 vaccine offered protection against the variant and cited data from an Oxford University lab study. The study on the company’s vaccine, Vaxzevria, demonstrated that following a three-dose course, neutralising levels against Omicron were similar to those against Delta after two doses.

Despite this promising data, WHO officials have emphasised that there is not yet enough evidence to support the claim that Omicron is a mild variant. The technical lead on COVID-19, Maria van Kerkhove, expressed in a briefing in Geneva that the data on Omicron was still “messy”.

Omicron is now the dominant variant in the US and is rapidly becoming more dominant in most of western Europe. In Britain, Omicron has caused daily infections to soar beyond 100,000.

Whilst COVID-19 hospitalisations and deaths in the UK have been more gradual, Raghib Ali, a senior clinical research associate at the University of Cambridge, has warned that even a small proportion of hospitalisations could be enough to overwhelm the healthcare system. However, Ali expressed that the UK data was encouraging and “may help justify the government’s decision not to expand restrictions on social gathering over Christmas in England”.