Acknowledgements
We thank the PT manufacturing team for their contributions that lead to this Phase 1 trial. We thank Sunnybrook Research Institute for the GMP operational support (see Supplementary Note). We thank Dr. W Rod Hardy for the Delta (B.1.617.2) spike construct, and Karen Colwill and Bhavisha Rathod for assistance with logistics. A medical writer employed by PT provided the first draft of the manuscript and editorial assistance.