a, Multiplex SARS-CoV-2 IgG response by MIA after prime-boost vaccination. Time course of IgG responses are shown for three ChAdOx1 nCoV-19 prime-boost groups; SD/SD: two standard doses administered either 28 (n = 10 participants, except for on day 42 where samples from only 9 participants were available) or 56 (n = 20 participants, except for on days 28, 70 and 84 where samples from only 19 participants were available) days apart, SD/LD: standard dose prime followed by low-dose boost 56 d apart (n = 32 participants, except for on days 70 and 84 where samples from only 29 and 31 participants were available, respectively) and for two doses of MenACWY comparator vaccine (n = 10 participants). Dashed vertical lines show time points at which boosting occurred. Plot shows the median and IQR. AU ml−1, arbitrary units per milliliter. Left: anti-RBD responses. Right: anti-spike protein responses. The dashed line indicates responses in 30 participants who received only one dose of ChAdOx1 nCoV-19 and were seropositive at baseline (seropositivity threshold defined as anti-spike IgG > 1,000 AU ml−1). b, Live SARS-CoV-2 MNA80 after prime-boost vaccination. Time course of microneutralization titer at IC80 is shown for three ChAdOx1 nCoV-19 prime-boost groups; SD/SD: two standard doses administered either 28 (n = 10 participants, except for day 42 time point where samples from only 9 participants were available) or 56 (n = 19 participants) days apart; SD/LD: standard dose prime followed by low-dose boost 56 d apart (n = 24 participants) and for two doses of MenACWY comparator (n = 10 participants). Error bars show medians and IQRs. To normalize data across assay runs, a reference sample was included in all assay runs and test samples normalized to this value by generating log10 ratios. Dashed lines show the upper limit of assay (values outside this range set to 640). The lower limit of the normalized data was set to 5. c, IFN-γ ELISpot response to peptides spanning the SARS-CoV-2 spike vaccine insert after vaccination with ChAdOx1 nCoV-19: the total ex vivo T cell response to the SARS-CoV-2 spike vaccine insert encoded within the vaccine is shown over time (IFN-γ ELISpot; spot-forming cells (SFCs) per 106 peripheral blood mononuclear cells (PBMCs), calculated by summing the responses to peptide pools corrected for background; Methods). Response is shown as the median with IQR per vaccination regimen; D56 (n = 4 at days 0 and 28, n = 10 participants at day 35, n = 20 at day 70 and n = 19 at day 84); SD/LD: standard dose prime and low-dose boost vaccination (n = 9 for days 0 and 28, n = 31 at day 70 and n = 32 at day 84). Participants received a full or half-dose booster dose of ChAdOx1 nCoV-19 at day 56 (SD/SD D56, and SD/LD D56). The lower limit of detection is 48 SFCs per 106 PBMCs and is denoted by a dashed line. MenACWY (n = 79 at day 0, n = 43 at day 7, n = 44 at day 14, n = 69 at day 28, n = 42 at day 56 and n = 10 at days 70 and 84). d, NAb levels measured in pseudovirus assay (Monogram IC50) pseudovirus neutralization titers. Dots represent individual data points. Box plots represent median titers and IQR. Left: standard dose given 28 d apart (n = 10). Middle: standard dose given 56 d apart (n = 20). Right: dose-sparing regime (standard followed by half dose) given 56 d apart (n = 32). SD/SD D28: D0, n = 10; D28, n = 10; D35, n = 7; D42, n = 9. SD/SD D56: D0, n = 20; D28, D35 and D42 not performed; D56, n = 20; D70, n = 19. SD/LD D56: D0, n = 32; D28, D35 and D42 not performed; D56, n = 32; and D70, n = 29. Data for SD/SD D28 (a–d) were previously published and reproduced here from Folegatti et al.17 with permission from Elsevier.