Experts: Best treatment against omicron in short supply

The first generation of monoclonal antibody treatments are not effective against the COVID omicron variant, experts say, and the newer treatments are in short supply in Connecticut.

“Some of the now older ones don't seem to fit to omicron very well,” said Dr. Brooks Walsh, an emergency room physician at Bridgeport Hospital.

While doctors have said the omicron variant has produced milder symptoms than previous strains, Connecticut COVID hospitalizations are still on the verge of setting an all-time pandemic high.

According to Dr. Ulysses Wu, chief epidemiologist at Hartford HealthCare, there are three monoclonal antibodies they use against COVID, but “two of them are, for the most part, ineffective against omicron.”

A fourth monoclonal antibody treatment has been approved, but not for treatment of an active infection.

One of the three treatments, Sotrovimab, made by GlaxoSmithKline, is effective against omicron, according to Trinity Health’s chief clinical executive, Syed Hussain. He said they are “comfortable with our supply of this particular monoclonal antibody.”

Though he did not say there was a shortage, Wu said production has yet to reach full capacity.

“With the previous monoclonal antibodies against the previous variants, including delta, we have plenty of supply of,” he said. “Some of our monoclonals are in, I don’t want to say short supply, it’s just they were never in large supply and we're waiting for that to be ramped up. So they are in limited quantity at this point.”

The vast majority of coronavirus cases in Connecticut are not genetically sequenced, so doctors and patients rarely know which variant is causing an infection.

“Sequencing, in terms of viral sequencing, takes time, and it’s a special send-out tests in the lab. And not all specimens go to that lab,” Hussain said. “So we look at data, we look at what projections for this region and for the country are which include omicron on track to becoming the dominant strain.”

Because the variant causing an infection is unknown, and since there may be limited supplies of an effective treatment, Wu said the strategy is to “risk stratify.”

“We reserve the medication that works against omicron for those that may be the most sick, or maybe at most risk for developing complications,” he said, reserving the older treatments for patients who may not face as much risk.

“That is how we determine the allocation at this point.”

According to the federal Food and Drug Administration, “Monoclonal antibodies are laboratory-made molecules that act as substitute antibodies. They can help your immune system recognize and respond more effectively to the virus, making it more difficult for the virus to reproduce and cause harm.”

They’re not new to medicine — many monoclonal antibody treatments have been approved to fight or prevent various other ailments. But the FDA first approved a monoclonal antibody for the treatment of COVID-19 last November under an emergency use authorization.

The authorization for that first treatment, bamlanivimab, made by Eli Lilly, was revoked but, since then, several similar treatments have been approved and shown to be effective.

Though genetic sequencing is performed on only a small fraction of patients, it’s possible to look for a specific marker, called an s-gene dropout (also referred to as SGTF) to determine if a patient is infected with omicron.

As Yale researcher Nathan Grubaugh explained, if a sample has that SGTF, it’s likely — but not certain — to be omicron.

“The FDA had said that they would not be opposed to using SGTF as a diagnostic readout for clinical uses, but there are still problems,” Grubaugh said.

But those samples would have to be clinically verified against the Clinical Laboratory Improvement Amendments, standards set by the Centers for Medicare & Medicaid Services, which regulates testing.

“That’s not impossible, but it takes time,” Grubaugh said.

Only one diagnostic test, the ThermoFisher TaqPath COVID Combo Kit, can verify that sgene dropout.

“Changing the system to switch to use it for inpatients in the middle of the highest outpatient testing demand of the pandemic would have caused even further capacity issues,” Grubaugh said. “Changes like this are much easier to do when testing is low.”

But Grubaugh believes omicron, already confirmed to comprise more than 50 percent of the total number of tested samples, will soon be causing every infection, if it’s not already.

“It’s all moot now anyways,” Grubaugh said. “Just about all new admissions are omicron and hospitals have stopped ordering the old monoclonals.”

In addition to Sotrovimab, there have also been two oral antivirals approved for use, though those are in very limited supply so far, according to Walsh.

“The newer ones, the new oral agents that just got approved, they’re still working out how to get them to people,” Walsh said.