Many unknowns remain about protective role of COVID-19 antibodies
It is not yet clear whether COVID-19 antibodies are protective against reinfection, according to a briefing on antibody testing held by the Infectious Disease Society of America in which physicians also noted that antibodies are not “a license” to halt mitigation efforts that have been put into place in many states.
In acknowledging the keen interest in antibody tests among health care providers and the public, IDSA conducted an informal narrative review of available literature on antibody responses in COVID-19 infection.
Mary K. Hayden, MD, FIDSA, IDSA spokesperson and professor of internal medicine and pathology at Rush University Medical Center, explained that antibody tests are performed using the blood of a patient with confirmed COVID-19 infection to detect antibodies that the immune system produce in response to the infection.
“Most patients who develop and recover from COVID-19 infection will develop antibodies or will have detectable antibodies in their blood approximately 10 to 14 days after the onset of their illness,” Hayden explained. “The hope for antibodies has been that the detection of them in the blood represents protection for reinfection. That's really the million-dollar question.”
Hayden continued by noting that “we do not know” if patients with these antibodies are still at risk for reinfection.
According to Hayden, even if the antibodies are protective, the degree of protection is unknown and could wane over time. As a result, it should generally be assumed that people with antibodies could be at risk for reinfection and should not change their behavior in any way in regard to social distancing and other actions.
Liise-anne Pirofski, MD, FIDSA, IDSA spokesperson and Selma and Dr. Jacques Mitrani Chair in Biomedical Research and chief of the division of infectious diseases at Albert Einstein College of Medicine, concurred.
“Having antibodies is not a license to stop the mitigation guidelines and rules that are in effect in many states,” she said. “Having any antibody is not a license today, on April 24, to break with that policy.”
While antibodies will not enable the relaxation of mitigation policies, Hayden explained that antibodies and subsequent testing will be useful in determining the scope of COVID-19.
“Antibody testing is very important,” she said. “The first uses, once we’ve determined that the antibodies are accurate, will be for broad epidemiologic surveillance to understand what fraction of the population has been infected, which will give us better information about the proportion of asymptomatic patients or persons with COVID-19.”
She added that this information will help guide mortality estimates and inform projections about the trajectory of the virus over time as well as vaccine development, which will require antibody tests.
“What we are confronting here is a huge unknown. We absolutely do not know how many people have seen this virus and the problem is different in different places,” Pirofski added. “That is really the main point that I would like to make, other than to point out that the overarching concept of using antibodies is extremely important. This is a tried and true method for determining the prevalence of an infectious disease in a community.”– by Caitlyn Stulpin
Disclosures: Healio could not confirm relevant financial disclosures for Hayden or Pirofski at the time of publication.