Shown is a scattergram and correlation analysis of the neutralizing antibody titers and anti-spike IgG ELISA units for the 5-μg NVX-CoV2373 2-dose vaccine group (Group B) for younger adults 18 to 59 years (Panel A) and older adults 60 to 84 years (Panel B). Pearson correlations were calculated with 2-sided 95% CIs. The correlation plots were inclusive of paired specimens by the 2 assays at the Day 21 time point following first vaccination, as well as for paired results at the Day 35 time point following second vaccination. (A) 5 μg + Matrix-M1 (Group B)– 18–59 years [footnote for Fig 4A] * NCT04368988 –phase 1. (B) 5 μg Matrix-M1 (Group B)– 60–84 years. CI, confidence interval; ELISA, enzyme-linked immunosorbent assay; EU, endotoxin unit; IC, inhibitory concentration; IgG, immunoglobulin G; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.