With Omicron raising concerns about COVID vaccines' efficacy, drugmakers are stress-testing existing jabs while also racing to prepare new formulas, according to reports.

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All major drugmakers including Pfizer, Moderna, Johnson and Johnson, and AstraZeneca have said that they are working to quickly investigate and adapt their shots to a new and highly mutated strain of the virus. Pfizer and BioNTech said they are investigating the new, heavily mutated variant, the Wall Street Journal reported. The companies added they can adapt their mRNA vaccine within six weeks and start shipping batches within 100 days if an escape variant is identified.

Although the company offered reassurance that the fully inoculated people would have a "high level of protection against severe disease" from the new strain, there is, as yet, no conclusive evidence on how immune protection holds up against the heavily mutated variant.

According to the World Health Organisation (WHO), Omicron poses a "very high risk". The global health body said that scientists all over the world are working to understand Omicron, its risks and whether it causes severe disease, and vaccine effectiveness. The data will be available within two weeks.

Stephane Bancel, chief executive at Moderna, said that currently available vaccines for COVID-19 could likely be less effective against the new Omicron variant. He added that it will take several months before pharma companies can manufacture variant-specific jabs at scale, The Financial Times reported.

The University of Oxford, which makes the coronavirus vaccine with AstraZeneca, in a statement, said there was "no evidence so far" that existing vaccines would not continue to provide protection against Omicron, as they have for previous variants of concern. It added that they had the "necessary tools and processes in place for rapid development of an updated COVID-19 vaccine if it should be necessary".

Meanwhile, China on 30 November said it is ready to tackle the newly detected Omicron coronavirus variant, and it is confident that the country's mainstream tests will block community transmission. According to Xu Wenbo, from the Chinese Center for Disease Control and Prevention (CDC), the vaccines developed in China remain effective against the new mutated variant, yet to better cope it has made technological reserve preparations in vaccine development, Global Times reported.

Producers of inactivated vaccine, protein subunit vaccine or adenovirus vector vaccine have set about studying the new variant and they are in the process of gene sequencing design, Xu, head for National Institute for Viral Disease Control and Prevention with the China CDC, said at a press conference on Tuesday.

Russia's Gamaleya Institute also believes that both Sputnik V and Sputnik Light will neutralise Omicron. The Gamaleya Institute, based on existing protocols of immediately developing vaccine versions for variants of concern, has already begun developing the new version of the Sputnik vaccine adapted to Omicron, said Kirill Dmitriev, CEO of the Russian Direct Investment Fund. However, in an unlikely case, such modification is needed, the new Sputnik Omicron version can be made ready for mass-scale production in 45 days, he added.

As per Bancel, the high number of Omicron mutations on the spike protein, which the virus uses to infect human cells, and the rapid spread of the variant in South Africa, suggested that the current crop of vaccines may need to be modified next year. He said scientists were worried because 32 of the 50 mutations in the Omicron variant are on the spike protein, which current vaccines focus on to boost the human body's immune system to combat COVID.

As there is still a lack of reliable data on vaccine efficacy against Omicron, WHO's Chief Scientist Soumya Swaminathan told the FT that "we believe it's premature to draw any conclusions about the efficacy of vaccines against Omicron".

"WHO has convened all our expert groups and scientists are working on experiments to test neutralisation capacity of stored sera from recovered patients or vaccinated individuals against the new variant. This will take a few weeks." Swaminathan said "we need to be patient", pending full "clinical effectiveness studies to truly understand if this variant is able to overcome the immunity generated by existing vaccines".