A study conducted at the David Geffen School of Medicine, University of California, Los Angeles confirmed the short duration of ELISA-detected IgG antibody against SARS-CoV-2.  This trial comprised 34 participants of whom 30 were confirmed as being infected with COVID-19 applying polymerase-chain reaction assay.  The four non-confirmed patients demonstrated symptoms compatible with COVID-19 and were previously in close contact with known infected individuals. All participants demonstrated mild symptoms of COVID-19 and ranged in age from 21 to 68 years.

Blood samples were obtained over a period of 37 through 86 days after onset of symptoms.  Serum samples were analyzed by enzyme-linked immunosorbent assay [ELISA] to detect anti-SARS-CoV-2 spike receptor binding domain IgG.  The study demonstrated that COVID-19 antibody had a half life between 26 to 60 days.

The authors of the letter to the NEJM* opined that the protective role of antibody against SARS-CoV-2 is unknown and that the rapid decay in antibodiy titer as detected by the ELISA was consistent with concurrent studies.  The authors warned against the validity of “immunity passports.”  The development of herd immunity and more importantly the potential durability of antibody stimulated by vaccines.

 *Ibarrondo, F.J.et al Rapid Decay of Anti-SARS-CoV-2 Antibodies in Persons with Mild COVID-19 - New England Journal of Medicine. DOI.10.1056/NEJM2025179. July 21, 2020.