Antibodies now being tested as a prevention tool against COVID-19

If you're bitten or scratched by an animal with rabies, your doctor can give you a shot to prevent the virus from taking hold in you and causing an infection. The same concept is now being put to the test for the coronavirus.

Most people who get sick with COVID-19 produce antibodies in their blood that seem to protect them from reinfection. A study is now underway to see whether an infusion of those antibodies can protect someone who has been exposed to the virus and is at high risk of infection.

One of the first volunteers for this study is a physician who treats transplant patients at the Johns Hopkins University School of Medicine. Jonathan Orens had a close brush with the coronavirus involving not his work, but his family.

His daughter from Los Angeles wanted to come home to be near her sister, who was about to give birth to her first baby. Orens says the traveling daughter was careful about protecting her health in Los Angeles and did everything she could think of to stay safe on her flight to Baltimore.

She wore a mask, she wore gloves, she had sanitizer, she had wipes, he says.

The load on the plane was relatively small. They chose the Fourth of July as a travel day, knowing that even fewer people were likely to be traveling that day. We actually bought the two seats in the row to keep her away from everybody else.

She wore masks through the airports and in the car ride back to her parents' house. Once there, she kept her distance from them.

Just to be sure, about a week after she arrived, she and her parents went for coronavirus testing.

Though she had no symptoms, "she was positive," Orens says. "And fortunately my wife and I were negative." But they were still at high risk of contracting the disease, given the close contact with their daughter.

As luck would have it, one of Orens' colleagues at Hopkins was just starting a study to see if purified blood serum from people who have recovered from COVID-19 — called convalescent plasma — could prevent the disease in someone else. Orens and his wife, who are in their early 60s, are entering an age group at higher risk of serious disease if infected with the coronavirus. They signed up for the experimental treatment.

Half the people in this clinical trial get an intravenous infusion of convalescent plasma, while the other half get an infusion of blood serum that had been donated before the pandemic emerged (so it lacked protective antibodies). Neither the participants nor the doctors treating them know who's getting what.

The infusion took about an hour, Orens says. "I didn't feel anything except for the pinprick from the IV, and we went on our merry way."

He now returns to the clinic for regular blood tests.

We'll follow him along to see if he develops symptoms and if he turns positive, says Dr. Shmuel Shoham, who is directing the study.

Shoham says he plans to enroll up to 500 patients — though, in the best-case scenario, if the treatment is highly effective he won't need to study that many people.

In addition to recruiting patients in Baltimore, "right now we have sites in Houston, sites in Alabama," Shoham says. "We're opening up additional sites in Dallas and Arizona. We have sites all over Southern California."

He's also involved in a second study that looks at whether plasma will prevent serious illness in people who are infected but not sick. He says if both of these strategies work, they could help a lot of people, even in the absence of a vaccine.

That would give people a lot of confidence, I think, to go back to school, go back to work, he says, because if somebody gets sick it's not a tragedy --because we can protect them and protect those around them.

These studies are among a growing number of experiments involving convalescent plasma, both as preventive measures and as treatments for COVID-19.