Comparison of assays used to detect antibody response in COVID-19 vaccine trials: Results from of a UK multi-Centre randomised controlled trial to determine the immunogenicity responses of COVID-19 vaccines administered concomitantly with seasonal influenza vaccines (ComFluCOV).
Lazarus R., Harris R., Thirard R., Baos S., Culliford L., Todd R., Hallis B., Charlton S., Finn A., Snape MD., Rogers CA., ComFluCOV Trial Investigators None.
BackgroundThe ComFluCOV trial tested the safety and immunogenicity of COVID-19 and influenza vaccines co-administration. Binding and functional SARS-CoV2 anti-spike responses were measured using assays developed in response to the COVID-19 pandemic. The three assays used to measure the immunogenicity outcomes are reported here and their performance compared to inform future vaccine development.MethodsAdults aged over 18 were vaccinated with a COVID-19 and either an influenza vaccine or saline placebo. Serum sampled one month after vaccination was used to measure SARS-CoV2 anti-spike antibody concentrations using a commercial in-house enzyme-linked immunosorbent assay (ELISA), a commercial fast throughput electrochemiluminescence immunoassay (ECLIA) and a viral neutralisation assay (VNA). Geometric mean ratios were used to compare the response to COVID-19 with or without influenza vaccine with a threshold of 0.67 considered non-inferior. The relationship between the different assays was examined using Kendall rank correlations.ResultsThe geometric mean ratios exceeded 0.67 using all assays for all COVID-19 and influenza vaccine combinations tested. Moderate rank correlations were found between the three assays.ConclusionAll three assays confirmed that vaccine co-administration did not significantly impact on immunogenicity of any of the vaccines tested.Trial registrationISRCTN14391248, registered on 17/03/2021.