WASHINGTON (BLOOMBERG) - Powerful drugs recently authorised by the US that may prevent those at the earliest stages of Covid-19 from suffering severe disease present thorny new challenges, including who will get them and where they'll be administered.
Antibody treatments, like one from Regeneron Pharmaceuticals that was used to treat President Donald Trump, are often administered to patients at their peak contagiousness. Regeneron's drug, along with a therapy from Eli Lilly & Co, were authorised by the US Food and Drug Administration for use within 10 days following patients' first symptoms, and doctors will be racing against time to give them.
Though the US has spent hundreds of millions of dollars to snap up the antibody treatments, they will be rationed due to limited supplies. Officials are working to establish sites to infuse the medications to patients with mild to moderate disease who had until recently been advised to stay home during an unprecedented surge in cases.
"Having a patient who has a coronavirus infection come to a hospital setting to get an IV injection is a problem, mostly because you have to isolate the patients from the rest of the patient population," Operation Warp Speed leader Moncef Slaoui said in an interview.
"That's what we are working very hard to solve."
The Lilly and Regeneron monoclonal antibodies mimic proteins the body normally makes to block the virus from entering cells; they were cleared by the FDA earlier this month.
They're the first drugs authorised specifically for non-hospitalised patients, and are targeted at those at risk of severe symptoms because of older age, obesity and other chronic conditions.
While Mr Trump touted Regeneron's therapy after receiving it in October, infectious disease doctors note that the evidence supporting the drugs' use in Covid-19 is not yet definitive. Yet there's hope they could help the country battle its worst-ever coronavirus surge, as average daily infections soared to almost 170,000 over the last week.
About 90,500 Americans were hospitalised with Covid-19 as of Thursday, according to the Covid Tracking Project.
Coronavirus-beset hospitals are also grappling with more infected staff, said Ms Allison Suttle, chief medical officer at Sanford Health, a nonprofit health system based in South Dakota. Treatment that keeps patients from being admitted would offer a tantalising reprieve.
"That gives us a lot more breathing room in our hospitals," she said, "that relieves a lot of the issues we're having."
Physicians will refer patients for treatment, and in some cases emergency department providers can administer the drugs, US health officials said at a Nov 23 briefing. Yet access issues loom.
The US has paid Lilly US$375 million (S$502 million) to supply 300,000 vials of its antibody, bamlanivimab, over the next two months. It also awarded Regeneron US$450 million to make and supply enough doses of its antibody cocktail for another 300,000 patients through the end of January. Both companies intend to scale up supply for the US next year.
That still won't be enough for some 300,000 high-risk patients diagnosed each week, according to Lilly chief executive officer David Ricks.
The government is distributing the treatments to each state and territory according to the size of their outbreaks, with state and local health departments taking the lead from there.
Timely testing, a longstanding challenge in the US, is also a key factor. Testing giant Quest Diagnostics, which currently reports average turnaround times of two to three days, priorities results for certain patient groups, including those in long-term care facilities, but not based on individual risk factors.
"The sooner you have some of the signature symptoms, the sooner you get tested, the sooner you get results, the sooner you'll be a candidate for the medicine," Mr Ricks said in an interview.
Meanwhile, health officials are determining where and how to infuse the medicine to patients who are still in the early stages of the disease and may be highly infectious. Maryland is setting up four infusion sites around the state, including a Covid-19 field hospital at the Baltimore Convention Centre, said Howard Haft, an official with the Maryland Department of Health.
With about 1,100 doses of Lilly's bamlanivimab, "the challenge is identifying the right patients as early as possible to avoid unnecessary hospitalisations," Mr Haft said.
Health officials are looking at ways of prioritising patients for antibody treatment. Northwestern Medicine in Illinois is using a risk score based on factors like age and body mass index, said Dr Tina Stosor, a professor at Northwestern University Feinberg School of Medicine.
"People have been calling in from all over to get scheduled," she said.
Among the challenges for medical centres is keeping antibody infusion sites separate from other patients, especially those with cancer and autoimmune diseases. The risk of immunocompromised patients coming into contact with people infected with Covid-19 is discouraging some centres from providing the service.
The Ohio State University Wexner Medical Centre started administering Lilly's drug on Nov 16 in an unused auditorium.
Six patients can be infused at a time, with supervising nurses clad in protective gear. In the first week, 62 patients received the drug, said Dr Carlos Malvestutto, an infectious disease specialist who has worked on studies of both the Lilly and Regeneron drugs.
The centre has also discussed setting up a site that could be jointly staffed with other hospitals. They looked at doing so at a convention centre in Columbus, Ohio, but decided against it for now due to concerns about contagious patients exposing others in the well-trafficked downtown area, Dr Malvestutto said.
No matter where or how the drugs are given, quick testing and treatment are key, according to Dr Malvestutto.
"If you end up giving patients this treatment later in the disease," he said, "it's almost pointless."