An antibody cocktail now used to treat patients fighting COVID-19 could help prevent infections in those living with or caring for COVID patients, University of Virginia researchers involved in studying the drug say.
The cocktail, created by Regeneron Pharmaceuticals, has received U.S. Food and Drug Administration approval for use in treating COVID, but is now being studied as a possible preventative as well.
“It’s a phase 3 trial, which means we’re testing in patients now,” said Dr. William Petri, Jr., one of the trial’s leaders at UVa. “It appears that the antibodies in the cocktail act as almost instant immunity.”
The study is also being conducted at other hospitals around the country. Positive results in the trial could convince the FDA to make the treatment available to prevent COVID-19 after exposure to the virus.
Called REGEN-COV, the treatment received emergency use authorization in late November from the FDA to treat high-risk patients with mild to moderate disease. President Donald Trump received the therapy when he was hospitalized for coronavirus last year.
The treatment is infused into the bloodstream and is meant to mimic an immune response to infection. It provides passive immunity in that the patient’s body does not need to generate its own antibodies.
“Rather than waiting for your body to make the antibodies like with a vaccine, this is a shot of antibodies that immediately fight the spike proteins of the virus,” Petri said. “It’s not long-lasting like the vaccine, but it appears to prevent infections in people who are exposed to the virus.”
In early results from the study, the cocktail successfully stopped 100% of symptomatic COVID-19 infections among people who were exposed to the virus. It also helped those already infected but asymptomatic to limit the amount of virus in their bodies and led to quick recovery, usually within a week.
It does not, however, provide lasting immunity from the virus.
“It’s like turning the clock back by giving you antibodies before your body can make them,” Petri said. “The disadvantage, of course, is that it doesn’t last but it lasts long enough to make a difference in the disease’s outcome. Until we get everyone vaccinated, it gives something.”
The treatment is being tested as a way to help those whose family members contract COVID-19 or who are the primary caregivers for COVID patients. By boosting the person’s immunity, the cocktail could prevent infections of family members and limit the virus’ spread.
“It’s very effective at decreasing the severity of the disease and in a lot of cases it will prevent someone exposed from contracting it,” Petri said. “You would still need to get the vaccine so that your body could generate its own antibodies, but this could be used as a stop gap.”
A non-published analysis by Regeneron showed that in about 400 trial participants, 186 people received the cocktail and none developed symptomatic COVID-19. Of the 223 who received a placebo, eight developed symptomatic COVID-19.
Asymptomatic infections occurred in 15 of the antibody recipients and in 23 of the placebo recipients. Overall rates of infection, including both symptomatic and asymptomatic infections, were approximately 50% lower in the antibody group.
The cocktail recipients had viral loads – the amount of virus in the body – significantly lower than those who who did not receive it. They also all recovered within seven days while 40% of those who did not receive the treatment had disease courses lasting three to four weeks.
There was one death and one COVID-19-related hospitalization in the placebo group and none in the antibody group.
The cocktail appeared to shorten the duration of viral shedding, the time when the virus is being manufactured in the body, which could shorten the time someone is able to spread the virus to others.
In both of the test groups, subjects reported some injection-site itching and irritation, but no other reactions.
The UVa research team in the Regeneron project is led by Petri and UVa COVID Clinic director Dr. Debbie-Anne Shirley.