inclusion criteria: 1. healthy human subjects who are between 18 and 65 years of age. 2. have completed a covid vaccine series with at least three doses of a licensed mrna vaccine at least 3 months prior. 3. hiv antibody negative. 4. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. 5. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. 6. for men, using barrier contraception for the duration of the study. 7. no history of covid infection or history of documented covid infection at least 6 months prior, dated from either a self-reported positive rapid antigen test or positive pcr test (self-reported or documented). for participants with a history of covid infection, anti-nucleocapsid antibodies will be measured prior to enrolment to confirm infection.

inclusion criteria: 1. healthy human subjects who are between 18 and 65 years of age. 2. have completed a covid vaccine series with at least three doses of a licensed mrna vaccine at least 3 months prior. 3. hiv antibody negative. 4. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. 5. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. 6. for men, using barrier contraception for the duration of the study. 7. no history of covid infection or history of documented covid infection at least 6 months prior, dated from either a self-reported positive rapid antigen test or positive pcr test (self-reported or documented). for participants with a history of covid infection, anti-nucleocapsid antibodies will be measured prior to enrolment to confirm infection.

inclusion criteria: healthy human subjects who are between 18 and 65 years of age. have completed a covid vaccine series with at least three doses of a licensed mrna vaccine at least 3 months prior. hiv antibody negative. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. for men, using barrier contraception for the duration of the study. no history of covid infection or history of documented covid infection at least 6 months prior, dated from either a self-reported positive rapid antigen test or positive pcr test (self-reported or documented). for participants with a history of covid infection, anti-nucleocapsid antibodies will be measured prior to enrolment to confirm infection.

inclusion criteria: healthy human subjects who are between 18 and 65 years of age. have completed a covid vaccine series with at least three doses of a licensed mrna vaccine at least 3 months prior. hiv antibody negative. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. for men, using barrier contraception for the duration of the study. no history of covid infection or history of documented covid infection at least 6 months prior, dated from either a self-reported positive rapid antigen test or positive pcr test (self-reported or documented). for participants with a history of covid infection, anti-nucleocapsid antibodies will be measured prior to enrolment to confirm infection.

inclusion criteria: healthy human subjects who are between 18 and 65 years of age. have completed a covid vaccine series with at least three doses of a licensed mrna vaccine at least 3 months prior. hiv antibody negative. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. for men, using barrier contraception for the duration of the study.

inclusion criteria: healthy human subjects who are between 18 and 65 years of age. have completed a covid vaccine series with at least three doses of a licensed mrna vaccine at least 3 months prior. hiv antibody negative. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. for men, using barrier contraception for the duration of the study.

inclusion criteria: healthy human subjects who are between 18 and 65 years of age. have completed a covid vaccine series with three doses of a licensed mrna vaccine at least 3 months prior. hiv antibody negative. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. for men, using barrier contraception for the duration of the study.

inclusion criteria: healthy human subjects who are between 18 and 65 years of age. have completed a covid vaccine series with three doses of a licensed mrna vaccine at least 3 months prior. hiv antibody negative. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. for men, using barrier contraception for the duration of the study.

inclusion criteria: healthy human subjects who are between 18 and 65 years of age. have completed a covid vaccine series with two doses of a licensed mrna vaccine at least 3 months prior. hiv antibody negative. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. for men, using barrier contraception for the duration of the study.

inclusion criteria: healthy human subjects who are between 18 and 65 years of age. have completed a covid vaccine series with two doses of a licensed mrna vaccine at least 3 months prior. hiv antibody negative. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. for men, using barrier contraception for the duration of the study.

inclusion criteria: 1. healthy human subjects who are between 18 and 65 years of age. 2. have completed a covid vaccine series with two doses of a licensed mrna vaccine at least 3 months prior. 3. hiv antibody negative. 4. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. 5. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. 6. for men, using barrier contraception for the duration of the study.

inclusion criteria: 1. healthy human subjects who are between 18 and 65 years of age. 2. have completed a covid vaccine series with two doses of a licensed mrna vaccine at least 3 months prior. 3. hiv antibody negative. 4. able to understand and comply with protocol requirements and instructions; able to attend scheduled study visits and complete required investigations. 5. for women, negative pregnancy test and for those women of child-bearing potential practising two acceptable forms of contraception for the duration of the study. 6. for men, using barrier contraception for the duration of the study.