Treatment and Research

“The goal is to build a convalescent plasma capability within the DoD, both on the collection and on the treatment side,” said Andrew Cap, MD, PhD, director of research at the Army Institute of Surgical Research in San Antonio, TX, who helped draft a CCP protocol for the DoD.

When an individual is infected, the immune system produces antibodies to attack the invading pathogens, according to recent research. Neutralizing antibodies cling to a virus and keep it from entering cells, thereby neutralizing it. Not all antibodies are neutralizing, however.1

“Antibodies come in different flavors, some of them are neutralizing and some of them are non-neutralizing and we don’t know exactly which individuals are developing what type of antibody,” said Shelly Krebs, chief of B Cell Biology Core at Walter Reed Army Institute of Research (WRAIR) Military HIV Research program.

Research to date indicates that patients who have recovered from COVID-19 produce varying antibody responses. Some have a lot of neutralizing antibodies in their plasma; some have almost none.

To know whether an individual’s CCP has enough of the neutralizing antibodies requires testing the plasma for antibody levels, said Kayvon Modjarrad, MD, director of the Emerging Infectious Diseases Branch at WRAIR. It also requires understanding what level of antibodies is needed to provide protection, a question that Modjarrad’s lab is trying to answer.

A transfusion of antibodies is generally expected to help patients whose own immune systems are unable to mount a sufficient response and to provide some short-term immunity from reinfection.

“It is likely that a person with COVID-19 who receives CCP will also still develop their own immune cells and produce antibodies to fight the virus if that person is re-exposed in the future,” said Todd Gleeson, MD, officer-in-charge of the Navy Bloodborne Infection Management Center in Bethesda, MD.

Convalescent plasma also provides a source for a potential preventative and therapeutic agent, monoclonal antibodies.

Krebs and her team at WRAIR have isolated neutralizing antibodies from CCP samples that can target SARS-CoV-2 at the atomic level, something convalescent plasma cannot do. The group plans to test monoclonal antibodies in animals this summer.

“We know where and how well it’s going to target, and we know the kinetics of how long it will last in the body and how long it will provide protection,” Modjarrad said.

  1. Chen L, Xiong J, Bao L, Shi Y. Convalescent plasma as a potential therapy for COVID-19. Lancet Infect Dis. 2020 Apr;20(4):398-400.