What are “antibody treatments” for COVID-19?
“Convalescent Plasma” could treat COVID-19
During the 1918 influenza pandemic, doctors found that giving blood from those who had recovered to those currently suffering from the flu could provide useful antibodies to help fight the infection. Since then, convalescent plasma treatment has been used in many infections, including severe flu, MERS, and SARS. Unfortunately, and despite high hopes, SARS-CoV-2 convalescent plasma given to those acutely ill with COVID-19 has proven to have only a marginal benefit. Two potential reasons for its mediocre efficacy might be that the levels of protective antibodies present in survivors fades too quickly or too variably and/ or the resulting level of neutralizing antibodies may be too dilute to make a meaningful dent in the viral load of an infected individual, particularly in those less able to mount a robust immune response.
“Enriched” antibody treatment might help bridge the gap until there is a vaccine
Antibody treatment, whether a monoclonal antibody might be used to treat active infection, to prevent infection in high risk people who have been exposed, or even as prophylaxis for front line workers at high risk of infection. Since the beginning of the pandemic, development of antibody treatments for COVID-19 has skyrocketed — currently there are more than a hundred antibody treatments in various stages of development. By June 2020, four had already progressed into human trials, providing hope that a few might be ready by this fall. Researchers, including Harvard T.H. Chan School of Public Health professor of immunology and infectious diseases Phyllis Kanki, caution that not everything works as planned outside of research studies and that it can take time to get the right antibody. Biotech experts, however, have remained more hopeful for a shortened timeline, with many manufacturers willing to take more financial risk in the current pandemic atmosphere.
Could an “antibody cocktail” containing 2 or more enriched monoclonal antibodies work even better?
On Tuesday September 29, 2020, Regeneron Therapeutics held a press release which, along with their earlier work in a peer-reviewed journal published in August, presented additional results focused on patients not so sick as to need hospitalization. In an interview with CNN, Dr. Jeanne Marrazzo, director of the division of infectious diseases at University of Alabama at Birmingham, said the results appear “very promising.” “What I think is fascinating is that it shows that antibodies really matter and the antibody to the spike protein was really helpful, particularly when people made the antibodies themselves,” said Marrazzo. “Whether it’s antibody therapy or a vaccine that targets these proteins, it sounds like we are on the right track. I think that’s really encouraging.” She was also encouraged by the reduction in the amount of virus in people’s throats, which could in theory reduce the risk of infecting others. “If it plays out and you could treat people early and actually reduce the viral load in the nasopharynx, and they might be less infectious, that would be hugely helpful,” said Marrazzo. Jennifer Gommerman, a professor of immunology at the University of Toronto, also used the phrase “really promising:” “It appears that they’ve got positive results and that this antibody cocktail doses reduce the amount of time that the patients are sick, especially the patients that weren’t able to mount their own antibody response,” Gommerman said. “They’re obviously going to have to do much more human experiments and bigger trials to really make sure.
(Sky Pittson, MD, September 29, 2020)