COVID-19 Monoclonal Antibody Treatment: VAAAHS Research Shows How Therapy Affects Immune System's Natural Response to Virus

Published March 2022 in the journal Clinical Immunology, the study, titled “Effect of monoclonal antibody therapy of the endogenous SARS-CoV-2 antibody response,” was performed by analyzing the levels of antibodies present in unvaccinated Veterans who had or had not received monoclonal antibody treatment. The Veterans ranged in age from 23 to 94 years old, were currently experiencing mild to moderate COVID-19 symptoms and were at high risk of progressing to severe COVID-19 illness due to preexisting comorbidities.

Endogenous immunity refers to your bodies natural response to fighting off different pathogens. Specifically, the humoral response describes special, adaptive antibodies that target infections, such as the virus that causes COVID-19 symptoms.

“Because it was a new treatment, we weren’t entirely sure exactly what the clinical course would look like, or how people’s immune system after the infection would respond. That’s part of the reason we were trying to have a better sense from the serologic data, to see if they have the same level of the antibody response,” said Dr. Paul Kim, director of the LTC Charles S. Kettles VAMC Emergency Department.

Led by lead author Dr. Paul Kim, researchers focused on the number of antibodies present in a person’s system utilizing special serologic testing devices. Serologic tests can detect whether antibodies are developing quickly to respond to a new infection, known as IgM antibodies, or if they’re “long-term” antibodies that last for several months, known as IgG antibodies.

Without any monoclonal antibody treatment, the faster developing IgM antibodies start responding in about 5 days, and peak around two-weeks’ time. At that point, the slower developing, but longer lasting IgG antibodies continue to provide protection for the body against the virus. For individuals at risk of severe illness due to COVID-19, this delay can lead to poor health outcomes and potentially death.

Monoclonal antibody treatments are engineered to quickly provide antibody protection, blocking the virus from binding to receptors in the body.

“We found that the anti-S IgM was diminished in those Veterans that received the monoclonal antibody, meaning their own natural response to the virus was diminished,” Dr. Kim explained.

Researchers found that while the monoclonal antibody treatments were effective at reducing the risk of severe disease from COVID-19, the treatment significantly reduced the natural, quick responding IgM antibodies, particularly between 10 and 40 days after infection. The longer-term IgG antibodies were slightly reduced, but not as drastically as the IgM antibodies.

“The benefit of the treatment is that we treat you now, at the possible risk of hampering your immune system long term. It saves you now, but maybe we need to get you more immunity later,” said Andrew Siler, a clinical pharmacist at the LTC Charles S. Kettles VAMC and co-author of the study.

“We still need to be mindful, and careful, about receiving the proper immunizations after this monoclonal antibody treatment,” added Dr. Kim.

The study provides clues as to when those who’ve received the monoclonal antibody therapy may need to receive new or additional COVID-19 vaccinations, and sheds light for those who’ve received the monoclonal antibody treatment on what level of antibody protection remains in their body.

“Now that we’ve demonstrated that, how do we answer further questions like, ‘Do these individuals still benefit from being vaccinated or not? Are they more likely to get infections later?’ It takes us a step further in trying to answer all the questions that we need to know,” Siler explained.