The European Union's drug regulator on Thursday conditionally approved the use of Pfizer Inc's  antiviral COVID-19 pill for treating adults at risk of severe illness, as the region scrambles to boost its arsenal to fight the Omicron variant.

The endorsement by the European Medicines Agency (EMA) allows EU member states to deploy the drug after the regulator gave guidance for its emergency use late last year.

Italy, Germany and Belgium are among a handful of EU countries that have bought the drugs.

The United States in December authorised Paxlovid and Merck's MRK.N similar drug molnupiravir. 

Merck's pill is also under review in the EU, but is taking longer to approve because the company revised its trial data in November saying the drug was significantly less effective than previously thought.

(Reporting by Mrinalika Roy and Manas Mishra in Bengaluru; Editing by Shounak Dasgupta) ((mrinalika.roy@thomsonreuters.com; within U.S. +1 646 223 8780, outside U.S. +91 806749 8325))