By Manas Mishra and Michael Erman

(Reuters) -A panel of expert advisers to the U.S. Food and Drug Administration on Tuesday narrowly voted to recommend the agency authorize Merck & Co's antiviral pill to treat COVID-19.

The U.S. drugmaker published data last week suggesting that the drug was significantly less effective than previously thought, reducing hospitalizations and deaths in its clinical trial of high-risk individuals by around 30%.

Still, medicines like Merck's molnupiravir, developed with Ridgeback Biotherapeutics, are likely to become important therapeutic tools that people will be able to take at home as soon as COVID-19 symptoms arise.

A rival drug being developed by Pfizer Inc (NYSE:PFE), called Paxlovid, is particularly promising, having shown an 89% reduction in hospitalizations and deaths in its clinical trial. The FDA could consider that drug within the next few months.

The FDA's Antimicrobial Drugs Advisory Committee voted 13-10 to recommend the agency authorize the drug after discussing concerns that the drug could cause the virus to mutate as well as safety concerns about the potential for birth defects. Both FDA staff scientists and Merck have suggested the drug should not be recommended during pregnancy.

The vote comes as fears about the new Omicron variant have rattled financial markets and sparked concerns about the strength of the global economic recovery as the world continues to fight the coronavirus pandemic.

The oral therapies target parts of the virus that are not changed by mutations in the Omicron variant. They could become even more vital if vaccine-induced and natural immunity are threatened by the variant.