The mutational load of greater than 10−2 changes per base in huB cell huVHDJH-Cγ transcripts in COVID-19 mRNA- and RBD–KLH-vaccinated THX mice is also evocative of the heavy mutational load of COVID-19 mRNA vaccine-induced huIgG response in humans59–61, possibly reflecting the high immunogenicity of Spike S1 RBD62,63. The gene discussed is CTSG; the disease is COVID-19.