Immunosuppression and COVID-19 Boosters

The diphtheria/tetanus toxoids vaccine will be given to participants enrolled into Group 1 as a comparator vaccine to the mRNA COVID-19 booster vaccine with the aim of determining whether the results related to COVID-19 vaccine timing also apply to more traditional protein-based vaccines.

All participants will receive a COVID-19 booster vaccination at either week 0 or week 24 depending on their randomised study arm