Antibody-Dependent Enhancement Risk for SARS-CoV-2 Vaccine Developers

This article explores a phenomenon called Antibody-Dependent Enhancement (ADE).  This occurs when binding of a virus to non-neutralizing antibodies enhances its entry into host cells, and sometimes also its replication.

The clinical outcome in individuals where an immune response results in the production of non-neutralizing antibodies, either through natural infection or through vaccination, usually results in a more serious outcome after infection compared to those who are immunologically naive.

Prior observations of ADE in some early SARS and MERS vaccine candidates recommends consideration of vaccine design and extensive animal testing as we move forward with clinical trials for vaccines directed against SARS-CoV-2.

The article in the link discusses ADE at some length as it pertains to SARS-CoV-2.  The italicized section below was published in the News section of Nature Medicine, June 5, 2020, and written by Ken Garber:

“…There are mounting theoretical concerns that vaccines generating antibodies against SARS-CoV-2 may bind to the virus without neutralizing it. Should this happen, the non-neutralizing antibodies could enhance viral entry into cells and viral replication and end up worsening infection instead of offering protection, through the poorly understood phenomenon of ADE. ADE “is a genuine concern,” says virologist Kevin Gilligan, a senior consultant with Biologics Consulting, who advises thorough safety studies. “Because if the gun is jumped, and a vaccine is widely distributed that is disease enhancing, that would be worse than actually not doing any vaccination at all.”

Food and Drug Administration (FDA). (2020). Insight into FDA’s revised policy on antibody tests: prioritizing access and accuracy. Retrieved from source.

Garber, K. (2020). Coronavirus vaccine developers wary of errant antibodies. Retrieved from source.