Of the dozens of patients Dr. Jim Yates has treated for Covid-19 at his long-term care center in rural Alabama, this one made him especially nervous. The 60-year-old man, who had been fully vaccinated, was diagnosed with a breakthrough infection in late September. Almost immediately, he required supplemental oxygen, and lung exams showed ominous signs of worsening disease. Yates, who is medical director of Jacksonville Health and Rehabilitation, a skilled nursing facility 75 miles northeast of Birmingham, knew his patient needed more powerful interventions — and fast. Full coverage of the Covid-19 pandemic At the first sign of the man's symptoms, Yates had placed an order with the Alabama Department of Public Health for monoclonal antibodies, the lab-made proteins that mimic the body's ability to fight the virus. But six days passed before the vials arrived, nearly missing the window in which the therapy works best to prevent hospitalization and death. "We've been pushing the limits because of the time frame you have to go through," Yates said. "Fortunately, once we got it, he responded." Across the country, medical directors of skilled nursing and long-term care sites say they've been scrambling to obtain doses of the potent antibody therapies following a change in federal policy that critics say limits supplies for the vulnerable population of frail and elder residents who remain at highest risk of Covid infection even after vaccination. "There are people dying in nursing homes right now, and we don't know whether or not they could have been saved, but they didn't have access to the product," said Chad Worz, CEO of the American Society of Consultant Pharmacists, which represents 1,500 pharmacies that serve long-term care sites. Before mid-September, doctors and other providers could order the antibody treatments directly through drug wholesaler AmerisourceBergen and receive the doses within 24 to 48 hours. While early versions of the authorized treatments required hourlong infusions administered at specialty centers or by trained staff members, a more recent approach allows doses to be administered via injections, which have been rapidly adopted by drive-through clinics and nursing homes. Prompt access to the antibody therapies is essential because they work by rapidly reducing the amount of the virus in a person's system, lowering the chances of serious disease. The therapies are authorized for infected people who've had symptoms for no more than 10 days, but many doctors say they've had best results treating patients by day 5 and no later than day 7. After a slow rollout earlier in the year, use of monoclonal antibody treatments exploded this summer as the delta variant surged, particularly in Southern states with low Covid vaccination rates whose leaders were looking for alternative — albeit costlier — remedies.