As rates of COVID-19 infections rise during the holidays and omicron cases surface across the United States, drug companies Pfizer and Merck are preparing to launch the first COVID-19 pills. If authorized by the Food and Drug Administration, these at-home treatments could be prescribed by doctors and picked up at your local pharmacy to reduce the risk of becoming severely ill.

“In early clinical research studies, both [drugs] demonstrated a significant decrease in the progression of COVID-19 in high-risk patients,” said Dr. Roy M. Gulick, chief of the Division of Infectious Diseases at New York-Presbyterian/Weill Cornell Medical Center.

Both drug companies emphasize that their medications will likely be effective against the omicron variant.

Public health officials remain concerned about a pending winter surge. People with higher risk factors — the unvaccinated, immune compromised, elderly and those with chronic conditions — need the pills most and may benefit the most, said Dr. Arthur Kim, an infectious disease specialist at Massachusetts General Hospital.

But with both pills on the cusp of potential FDA authorization, physicians have expressed concern about uptake and access. One concern is that the pills need to be taken early — within the first three to five days after diagnosis.

They are most effective “before a person becomes critically ill,” said Dr. Paul Currier, director of the Respiratory Acute Care Unit at Massachusetts General Hospital. “Once a patient becomes critically ill, the virus has already caused a lot of inflammation in the body that likely cannot be stopped by medicines that only target the virus itself.”

That could pose a logistics challenge, experts said, as people with mild symptoms are currently encouraged to stay home to avoid spreading COVID-19 to others.

At first, the pills will only be available with a doctor’s prescription, and with health care resources still strained, “delays in testing and capacity will reduce their effectiveness in the real world,” Kim said.

Both treatments require patients to take several pills twice per day for five days.

But pharmaceutical executives are optimistic that the pills will make a significant dent in the pandemic.

Pfizer’s pill has the “potential to save the lives of patients around the world,” said Pfizer CEO Albert Bourla.

Bourla estimated that 1,200 deaths and 6,000 hospitalizations would be prevented for every 100,000 COVID-19 patients who take the pills.

But pharmaceutical companies say emphatically these pills should be used as a last resort and for patients who are already sick. Getting vaccinated is by far the safest and most effective way to prevent getting COVID-19, or becoming severely sick if you do.

“I want to emphasize that no one should use the existence of the pill as an excuse to avoid vaccination,” Bourla said.

“The best way to prevent getting seriously ill from COVID-19 is to use the strongest preventative measures we have: wearing masks and getting vaccinated,” Currier said.

When taken early, Pfizer’s treatment was 89% effective at reducing the risk of severe illness, hospitalization and/or death from COVID-19, according to the company. Merck’s pill, meanwhile, reduced the risk of severe illness, hospitalization and death by 30%, it said.

If authorized by the FDA, Merck and Pfizer’s COVID-19 pills could be available as early as next month.

Dr. Navjot Kaur Sobti is a cardiovascular disease fellow physician, rising interventional cardiology fellow and board-certified internal medicine physician at New York Presbyterian Hospital/Weill Cornell Medical Center. She is a member of the ABC News Medical Unit.