MILAN, Dec 17 (Reuters) - The EU drug regulator will not decide whether to approve Merck & Co"s (MRK.N) COVID-19 pill until after Christmas, a source with knowledge of the matter said, as the region scrambles to boost its arsenal of drugs to fight the Omicron variant. But the European Medicines Agency (EMA) will rule before Christmas on whether to give Gilead"s (GILD.O) intravenous antiviral drug Remdesivir full marketing approval, the source said. If the Merck ruling on molnupiravir comes in the new year, that would be later than expected. In November, the agency said it expected to complete by the year-end its review of the pill developed by Merck with Ridgeback Biotherapeutics. read more Responding to requests for comment on the status of its reviews, the EMA said on Thursday it would publish the opinions adopted by its human medicines committee (CHMP) by Friday midday. The EMA is due to hold its regular briefing with media on Dec. 21. In November, the EU regulator issued guidance to member states on using the pill even before final EU-wide approval. It advised it should be given within five days of first symptoms to treat adults who do not need oxygen support and are at risk of their disease worsening. read more The logo for Merck & Co. is displayed on a screen at the New York Stock Exchange (NYSE) in New York City, New York, U.S., November 17, 2021. REUTERS/Andrew Kelly Gilead Sciences Inc pharmaceutical company is seen after they announced a Phase 3 Trial of the investigational antiviral drug Remdesivir in patients with severe coronavirus disease (COVID-19), during the outbreak of the coronavirus disease (COVID-19), in Oceanside, California, U.S., April 29, 2020. REUTERS/Mike Blake Lab technicians work on investigational coronavirus disease (COVID-19) treatment drug "Remdesivir" at Eva Pharma Facility in Cairo, Egypt June 25, 2020. REUTERS/Amr Abdallah Dalsh 1/4 Gilead Sciences Inc pharmaceutical company is seen after they announced a Phase 3 Trial of the investigational antiviral drug Remdesivir in patients with severe coronavirus disease (COVID-19), during the outbreak of the coronavirus disease (COVID-19), in Oceanside, California, U.S., April 29, 2020. REUTERS/Mike Blake That was before the U.S. drugmaker released data suggesting the drug was significantly less effective than previously thought, reducing hospitalisations and deaths in its clinical trial of high-risk individuals by around 30%. Alongside vaccines, the at-home antiviral treatments are considered a critical weapon for fighting the virus nearly two years into the pandemic. The decisions come as the EU struggles to tame a spike in infections, which threatens to overwhelm healthcare systems and as Omicron"s rapid spread has prompted some governments to reimpose restrictions ahead of the Christmas holidays. read more The EMA gave conditional marketing approval for Remdesivir, sold under the brand name Veklury, in July 2020 and extended that for another year in May. read more Conditional authorisation allows approval of medicines that fulfil an unmet medical need with less complete data than normally expected, if the benefit of a medicine"s immediate availability to patients outweighs any risks, and requires a review at least once a year. read more Standard approval would last five years.