The Food and Drug Administration announced Wednesday it has greenlighted Pfizer's antiviral pills to treat COVID-19 for emergency use, allowing limited use of the drug in Americans as young as 12 who are at "high risk for progression to severe COVID-19." The new treatment option comes as doctors are facing a nationwide shortage of monoclonal antibodies to treat high-risk cases of the disease, with most formulas ineffective against the fast-spreading Omicron variant. Early data suggests Pfizer's pills, called Paxlovid, are effective against Omicron cases. The drugmaker says it works to block the ability of the virus to make copies of itself. "This authorization provides a new tool to combat COVID-19 at a crucial time in the pandemic as new variants emerge and promises to make antiviral treatment more accessible to patients who are at high risk for progression to severe COVID-19," the FDA's Dr. Patrizia Cavazzoni said in a statement on Wednesday. Pfizer first sought emergency use authorization for Paxlovid in November. The company said it was shown in clinical trials to cut the chances of hospitalization or death by 88% among adults at high-risk of severe COVID-19, compared to a placebo. Pfizer is also running clinical trials to gather data on its use in two other potential groups of patients: for treating cases in people at "standard risk," as well as for preventing disease in people who are household contacts of a COVID patient. If it proves safe and effective in those uses, the drugmaker could seek wider authorization from the FDA. Paxlovid treatment needs to begin within a few days of first developing symptoms. A course of treatment is made up of three tablets that are taken twice a day, in the morning and evening, over the course of five days, for a total of 30 pills. Two of the tablets are nirmatrelvir, an antiviral Pfizer designed to target SARS-CoV-2, and one is ritonavir, a drug that has also been used to treat HIV. Like with some other COVID-19 treatments that have been authorized by the FDA, the regulator will limit Pfizer's drug to only people at "higher risk of being hospitalized for COVID-19." That includes seniors and people with underlying conditions like heart disease or diabetes. Distribution of the drug will be controlled by the Biden administration, which purchased 10 million courses of the drug in November.