Serostatus cutoff levels and fold increase to define seroresponse to recombinant vesicular stomatitis virus - Zaire Ebola virus envelope glycoprotein vaccine: An evidence-based analysis

Vaccine. 2020 Jun 26;38(31):4885-4891. doi: 10.1016/j.vaccine.2020.04.061. Epub 2020 Jun 1.


The recombinant vesicular stomatitis virus - Zaire Ebola virus envelope glycoprotein (rVSVΔG-ZEBOV-GP) vaccine is a live recombinant vesicular stomatitis virus (VSV) where the VSV G protein is replaced with ZEBOV-GP. To better understand the immune response after receiving the rVSVΔG-ZEBOV-GP vaccine, the current analyses evaluated different definitions of seroresponse that differentiate vaccine and placebo recipients enrolled in a placebo-controlled clinical trial (PREVAIL; NCT02344407) in which a subset of the study participants had elevated baseline titers. Alternative values for serostatus cutoff (SSCO; 200-500 EU/mL) and/or fold rise (two- to five-fold) were applied to compare their ability to distinguish between participants receiving rVSVΔG-ZEBOV-GP or placebo. The results indicate that an SSCO of 200 EU/mL can be used to define seropositivity at baseline (i.e. pre-vaccination). The use of dual criteria of the same SSCO (200 EU/mL) together with a two-fold rise in antibody level from baseline provided the definition of seroresponse that maximized the statistical significance between vaccine recipients and placebo recipients post-vaccination. Clinical trial registration: NCT02344407.

Keywords: ELISA; Ebola virus; Seroresponse; Vaccination.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Antibodies, Viral
  • Democratic Republic of the Congo
  • Ebola Vaccines*
  • Ebolavirus*
  • Hemorrhagic Fever, Ebola* / prevention & control
  • Humans
  • Vesicular Stomatitis*
  • Viral Envelope


  • Antibodies, Viral
  • Ebola Vaccines

Associated data