Internal medicine

Disease

Immunization

Coronavirus disease 2019 (COVID-19)

Antibody response

Infectious disease (medical specialty)

Biology

Pandemic

Antibody

Virology

Antibody titer

Immunology

Neutralizing antibody

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)

Titer

Medicine

Vaccine

A correlate of protection (CoP) is urgently needed to expedite development of additional COVID-19 vaccines to meet unprecedented global demand. To assess whether antibody titers may reasonably predict efficacy and serve as the basis of a CoP, we evaluated the relationship between efficacy and in vitro neutralizing and binding antibodies of 7 vaccines for which sufficient data have been generated. Once calibrated to titers of human convalescent sera reported in each study, a robust correlation was seen between neutralizing titer and efficacy (ρ = 0.79) and binding antibody titer and efficacy (ρ = 0.93), despite geographically diverse study populations subject to different forces of infection and circulating variants, and use of different endpoints, assays, convalescent sera panels and manufacturing platforms. Together with evidence from natural history studies and animal models, these results support the use of post-immunization antibody titers as the basis for establishing a correlate of protection for COVID-19 vaccines.

Evidence for antibody as a protective correlate for COVID-19 vaccines