WHO says more research needed on vaccine efficacy against Omicron

By Mrinalika Roy and Emma Farge

Jan 11 (Reuters) - The World Health Organization said on Tuesday more research is needed to find out if existing COVID-19 vaccines provide adequate protection against the highly contagious Omicron variant, even as manufacturers develop next generation shots.

The global health agency's latest technical brief aims to answer some of the big outstanding questions about the heavily mutated variant which first emerged in November, such as on severity, transmissibility and ability to evade vaccines. It also fixes priorities for its member states.

But on one of the key questions of whether a new Omicron-specific vaccine was needed now, the U.N. agency did not have an immediate answer.

"Further research is needed to better understand Omicron's immune escape potential against vaccine- and infection-induced immunity, and Omicron-specific responses to vaccines," it said.

A WHO official had previously said this issue required "global coordination" and should not be left to manufacturers to decide alone.

Some vaccine makers are already developing next generation vaccines targeting the highly contagious variant first detected in Southern Africa and Hong Kong.

On Monday, Pfizer Chief Executive Albert Bourla said a redesigned COVID-19 vaccine that specifically targets the Omicron coronavirus variant would likely be needed and his company could have one ready to launch by March.

Rival Moderna Inc is also working on a vaccine candidate tailored to the Omicron variant of the coronavirus, but it is unlikely to be available in the next two months.

A WHO technical group has been meeting on vaccine composition in recent weeks and is expected to come up with a further statement later on Tuesday, a WHO spokesperson said.

Additional data on vaccine effectiveness against Omicron and the need for shots tailored towards the variant will be available in coming weeks, WHO said in the statement.

It urged countries and partners to study vaccine effectiveness and impact.

The agency said early data suggests that homologous and heterologous booster doses increase vaccine effectiveness against Omicron infection and symptomatic disease compared to Delta, but one study has shown declining effectiveness of booster doses against symptomatic disease caused by Omicron.

Analysis by the UK Health Security Agency has shown that booster jabs are providing high levels of protection for older people against severe disease from the Omicron coronavirus variant, but the duration of protection against mild symptomatic infection is more short-lived and drops to around 30% by about three months.

(Reporting by Mrinalika Roy and Emma Farge, Editing by Alexandra Hudson)

((mrinalika.roy@thomsonreuters.com; within U.S. +1 646 223 8780, outside U.S. +91 806749 8325;))