Monoclonal antibodies were originally used in cancer treatment, I had them with my own treatment for lymphoma. There was some controversy when they started using them for Covid that it would deplete supplies for cancer treatment, so maybe this a subtle comment on that? Very obscure if you don't know the back story though! Sounds like a convoluted message anyway, I guess "trust science" being the gist of it. But also some cancer patients immune systems were too weak for the vaccine if I am not mistaken, it was part of why they tried to separate the advice for shielding the vulnerable and give them extra precautions in the UK during the pandemic.