CT doctors: ‘Mixed’ results on plasma COVID treatment
Research is “mixed” on the value of plasma from patients who have survived the coronavirus, experts say. The once often used treatment is now a rare choice for doctors, and then only under certain conditions.
“The data is still mixed that the convalescent plasma really does anything critical,” said Bruce Liang, dean of the UConn School of Medicine.
The idea is sound, according to Richard Martinello. Yale-New Haven Hospital, where Martinello is director of infection prevention, had like most other hospitals used blood — more accurately a part of the blood called sera — from recovered coronavirus patients to treat new patients.
“When somebody gets infected by COVID, their body has an immune response. And, as part of that immune response, their body develops antibodies against the virus itself,” Martinello said. “Those individuals who were sick, after they recover from their illness, they donate blood, the sera is removed from the blood.”
The sera, Martinello explained, is “the watery protein part that’s left over after the cells are removed.” It’s mostly water, but it contains proteins including antibodies.
“The amount of antibodies against COVID are measured, so there’s a general sense of how much anti-COVID antibodies are present within there,” he said. “And then it’s simply given to people.”
There have been several studies that show mixed results from the use of so-called convalescent plasma, most notably one conducted by researchers at the Mayo Clinic.
UConn, in collaboration with Jackson Labs, conducted its own study, looking at the antibodies present in health care workers who had contracted COVID but did not need to be hospitalized, other patients who were sick enough to be in the hospital and patients who had donated plasma after recovery.
Among other findings, that study concluded that the efficacy of convalescent plasma as a treatment for COVID-19 is questionable at best.
“Those patients who had recovered, their socalled convalescent plasma, the antibodies were low,” Liang said. “The convalescent plasma has a mixed picture. Some people got help with it, some people did not. Some of them will get well anyway, without the plasma. So you don’t know how much benefit it was actually conferring.”
At the start of the pandemic, treatment options were few. The coronavirus was a new and unknown pathogen, and doctors were using whatever they could to treat patients.
“The thought was, especially when there were very limited treatments against COVID, that this would be a reasonable approach, especially with no other alternatives available,” Martinello said. “Because there’s no very clear, impactful benefit, it remains something that is really just being offered, across Yale-New Haven health, we’re just offering it as a part of research now.”
Doctors at UConn Health are still using plasma from recovered patients to treat COVID, but only under very specific circumstances, as Lisa Chirch, an attending physician in infectious diseases explained.
“We are using it for select patients on a caseby-case basis,” she said.
What they’ve found, according to her colleague, Mauricio Montezuma, also an attending physician in infectious diseases at UConn Health, is that what matters most is the timing.
“The study from Mayo showed that patients that had received convalescent plasma early on in the disease course, and also that patients that were not on mechanical ventilation, had improved survival versus those that received a plasma later on or were on mechanical ventilation,” he said.
A COVID-19 infection is often characterized by two phases. There is the illness from the disease itself, and there is the damage from the body’s own immune response, often called a cytokine
storm.
“So it makes sense that early on where you had an active viral replication is where antibodies, which is what we are giving to the patient when we give them convalescent plasma, that those will be more active at the beginning of the disease course,” he said. “So we are still using plasma in those patients that are not extremely sick that are not in the ICU, and those that are not on mechanical ventilation.”
Chirch also noted that, unlike traditional medications,
physicians don’t necessarily know the level of antibodies, called a titre, in any plasma sample.
“All plasma is not created equal,” she said.
But that doesn’t mean plasma won’t be useful going forward. As new coronavirus variants emerge that may or may not be effectively prevented by vaccinations or treated by conventional medications, plasma that contains antibodies from recovered patients may be a tool to which doctors will return.