doi:10.1136/jitc-2020-000655 ►Additional material is published online only. To view, please visit the journal online (http:// dx. doi. org/ 10. 1136/ jitc- 2020- 000655). HAS and JLM contributed equally. PAP and JLG contributed equally. Accepted 18 February 2020 For numbered affiliations see end of article. Correspondence to Dr James L Gulley; gulleyj@ mail. nih.