Similarly, a highly significant increase in nAb ( p < 0.0001) was noted at 2 weeks post-vaccination for both vaccines relative to baseline, with only 3 and 5 seropositive donors receiving CS and CO respectively, failing to respond (Fig. 2b ).
2b ) across seronegative individuals relative to matched baseline as also evidenced in the larger study 23 , this did not reach statistical significance for CO vaccinees in this study.
Nevertheless, both vaccines possessed the potential to increase BA.1 and BA.2 titres, with differences post versus pre-vaccination reaching significance or near significance (Fig. 5c, e ).