With two highly effective coronavirus vaccines now being distributed across the country, the U.S. government’s announcement Thursday to set aside $2.6 billion for purchasing an antibody drug for COVID-19 may have raised a few eyebrows.

After all, the two currently authorized antibody drugs, from Regeneron and Eli Lilly, have not been widely used since the Food and Drug Administration cleared both in November. And the logistical issues that have hindered their launch haven’t been solved, either.

But Operation Warp Speed officials, including top FDA drug evaluator Janet Woodcock, are campaigning hard to change that, arguing the drugs are being “underutilized” in the COVID-19 response. Study results have shown the treatments can keep some sick patients from needing hospital care, which could be a huge benefit for healthcare systems under greater and greater strain.

“If we don’t do this,” Woodcock said on a conference call with reporters Thursday, “then the likelihood is that we’ll have even more overwhelmed hospitals and healthcare workers.”

Antibody drugs for COVID-19 gained notoriety when they were used to treat President Donald Trump and several other high-profile politicians in November. The treatments are made of synthetic antibodies that mimic the body’s natural defenses. While clinical trials are still ongoing, the data so far indicate they’re particularly beneficial for certain patients with mild or moderate symptoms whose own immune systems aren’t mounting a strong defense. The U.S. government initially pre-purchased 300,000 doses of both Regeneron’s and Lilly’s drugs and has since expanded deals with each company.

But the limitations of both drugs have become clear as they’ve been rolled out. The treatments must be infused in a healthcare setting, raising the risk that infected patients could endanger others at a hospital or clinic. They’ve only been authorized for those at high-risk of becoming hospitalized, a group the FDA has defined by age and certain underlying health conditions. And the drugs have to be given early in a person’s disease course, meaning fast testing and administration is needed to get the right patients treated at the right time.

Other problems have emerged as well. Woodcock noted the clinical evidence supporting each drug is not yet conclusive. Providers have to cover the costs of infusions while the associated codes are being entered into government systems. With rising COVID-19 case counts and intensive care units filling up across the country, hospitals are having difficulties staffing administration sites with healthcare workers. And that, in turn, has made antibody treatment difficult to get.

“Urging patients to go get treated when we couldn’t tell them where, and where things weren’t set up, was problematic,” Woodcock said.

Early last year, antibody drugs were viewed as a potential “bridge” to vaccines. Now, the fear is an opportunity has been missed for antibody drugs to help mitigate the pandemic’s impact. Between 20% to 25% of the government stockpile has been given to patients, officials said Thursday. With the vaccine rollout stumbling, though, there’s still a chance for antibodies to play an important role.

“We are working very hard with the government to rectify the situation,” Regeneron chief scientific officer George Yancopoulos said at the J.P. Morgan Healthcare Conference this week. “Obviously, and unfortunately, millions will continue to be infected and at risk over the next many months, and perhaps years until vaccines can be used to help create widespread immunity.”

Lilly CEO David Ricks told CNBC this week that utilization numbers are “climbing” but vary widely “state to state.” He noted, for instance, that the drugs have been widely used in Alabama.

“Anecdotally, I would say, we truly believe they have helped us turn the tide on our COVID outbreak here in south central Kansas,” in October and November, said Wes Hoyt, chief of operations at the Hutchinson Regional Medical Center, on the conference call.

In Michigan, the hospitalization rate two weeks after antibody treatment has been “pretty consistently around 5%,” compared to about 15% for high-risk patients given the placebo in clinical testing, said William Fales, medical director of the Michigan Department of Health and Human Services. Only about 10% of the 21,000 doses allocated to the state have been used, however.

But positive reports can only go so far in helping to boost use without improvements in access to the treatments. John Redd, the chief medical officer of the HHS Assistant Secretary for Preparedness and Responses office, said the government is focused on boosting supply, awareness and physical support to providers. The government has now secured options for up to 4.5 million antibody doses combined between Regeneron and Lilly. Some 660,000 had been allocated as of Wednesday, and states had delivered roughly 500,000 of those courses.

Government officials are also connecting with providers and local health departments and are ramping up an online treatment locator, into which all states will be required to input information. Reed said they’re sending emergency medical personnel from the National Disaster Medical System to help set up infusion centers in or around hospitals, citing efforts underway in California, Arizona and Nevada.