immune response of an interchangeable booster vaccine against covid-19 among individuals with risk factors for severity

Conditions: Comorbidities and Coexisting Conditions; Healthy

Summary: experimental, single-arm study in participants with comorbidities, previously immunized with 2 doses of coronavac, who will receive a booster vaccine with 1 dose of the oxford/astrazeneca vaccine.

intervention: oxford/astrazeneca - 0.5 ml single dose, intramuscular in deltoid, with an interval of 180 days (+/- 30 days) from the 2nd dose of the initial vaccination schedule with coronavac inclusion criteria: * have voluntarily participated and be in regular follow-up monitoring by the covacmanaus study; * have completed the vaccination schedule with 2 doses of coronavac, as per the covacmanaus study protocol for at least 180 days (+/- 30 days); * demonstrate availability to be followed during the follow-up period defined in the study, through visits, telephone contacts or other digital means of communication; * accept to participate in this new study for 6 (six) months. exclusion criteria * confirmed diagnosis of covid-19 within the last 28 days (antigen test or rt-pcr). in this situation, vaccination can be postponed until the participant completes 30 days; * report of fever within 72 hours prior to vaccination (inclusion can be postponed until the participant completes 72 hours without fever and covid-19 is discarded); * having received live attenuated virus vaccine in the last 28 days or inactivated vaccine in the last 14 days prior to inclusion in the study; * any other condition that, in the opinion of the principal investigator or its medical representative, could jeopardize the safety or rights of a potential participant or prevent them from complying with this protocol; * pregnancy or lactation. type of study/study design: experimental, single-arm study in participants with comorbidities, previously immunized with 2 doses of coronavac, who will receive a booster vaccine with 1 dose of the oxford/astrazeneca vaccine. sample size: all active participants from the covacmanaus study (up to 5071) primary outcome: detection and titration of antibodies against sars-cov-2 before (d0), at d90 and d180 after booster vaccination secondary outcomes: * profile of the cell-mediated immune response in a subgroup of participants, before (d0), at d90 and d180 after booster vaccination; * ability to neutralize antibodies in a subgroup of participants before (d0), in d90 and d180 after the vaccine booster; * memory cell populations in a subgroup of participants before (d0), in d90 and d180 after booster vaccination. * detection and titration of antibodies against sars-cov-2 and its association with the history of physical activity or sedentary lifestyle.

Eligibility criteria:
inclusion criteria: * have voluntarily participated and be in regular follow-up monitoring by the covacmanaus study; * have completed the vaccination schedule with 2 doses of coronavac, as per the covacmanaus study protocol for at least 180 days (+/- 30 days); * demonstrate availability to be followed during the follow-up period defined in the study, through visits, telephone contacts or other digital means of communication; * accept to participate in this new study for 6 (six) months. exclusion criteria * confirmed diagnosis of covid-19 within the last 28 days (antigen test or rt-pcr). in this situation, vaccination can be postponed until the participant completes 30 days; * report of fever within 72 hours prior to vaccination (inclusion can be postponed until the participant completes 72 hours without fever and covid-19 is discarded); * having received live attenuated virus vaccine in the last 28 days or inactivated vaccine in the last 14 days prior to inclusion in the study; * any other condition that, in the opinion of the principal investigator or its medical representative, could jeopardize the safety or rights of a potential participant or prevent them from complying with this protocol; * pregnancy or lactation.

Keywords: covid19 vaccine chadox1-s/ncov-19 [recombinant]