Figure 4.

Early and late CD4+ T cell responses to SARS-CoV-2 S. The cohort of acute donors was divided by ≤14 days PSO (early) and 15+ days PSO (late), and the PBMCs were tested for CD4+ T cell reactivity to SARS-CoV-2 spike by AIM and IFNγ ICS. The magnitude of spike-specific CD4 reactivity is shown for mild (n = 18, blue), moderate (n = 35, yellow), severe (n = 32, red), or all (n = 85, grey) COVID-19 donors (3 mild and 1 severe were excluded from the graph because the days PSO was not reported). The data are shown for the entire cohort and separated for side-by-side comparisons of early and late PSO within disease severities in AIM (A) and IFNγ (B) ICS. The same data are plotted as shown to compare the T cell responses in AIM (C) and IFNγ (D) ICS within disease severities. Additionally, pie charts show the frequency of the response for each level of disease severity. The y-axis starts at the LOD and the dotted line represents the LOS, while the solid lines or bars represent geometric mean. p-values are calculated by Kruskal–Wallis across all disease severities and Mann–Whitney U tests are applied as indicated by the symbols when significant. Chi-squared test is applied to the frequencies of response as indicated by the p-values below the pie charts. * p < 0.05, ** p < 0.01, *** p < 0.001.