Phase II/III Study of the AVX/COVID-12 Vaccine Against COVID-19 Applied as a Booster.

This is a phase II/III parallel, double-blind, active-controlled, non-inferiority study to evaluate immunogenicity and safety of a booster immunization scheme of a single intramuscular dose of the recombinant vaccine against SARS-CoV-2 (AVX/COVID-12 vaccine) based on live recombinant Newcastle disease virus (rNDV) vector in healthy adults with a history of vaccination against COVID-19. The study is divided into two phases with immuno-bridging and 3000 healthy subjects showing evidence of prior immunity to SARS-CoV-2 are estimated to enrol. To verify non-inferiority in a determined number of subjects an intramuscular dose of the COVID-19 vaccine (ChAdOx-1-S[recombinant]) shall be used as active control in originally randomised subjects. The study shall be carried out in several sites of clinical research in Mexico.

Inclusion Criteria:People ≥18 years old.Any genre.Have received their informed consent.Negative PCR test for SARS-CoV-2 during the screening visit.Negative pregnancy test in women with child-bearing potential.Commitment to maintain adequate prevention measures to avoid contagion by SARS-CoV-2 throughout their participation in the study considering their strict following for the first 14 days after the baseline visit (use of face masks in closed places, social distancing measures in open spaces and frequent handwashing).Have been vaccinated with any of the approved vaccines against SARS-CoV-2 (at least once).Exclusion Criteria:History of hypersensibility or allergy to any of the vaccine compounds.History of severe anaphylactic reactions of any cause.Fever at the baseline visit.Active participation in any other clinical trial or experimental intervention within last 3 months.Have received any vaccine (experimental or approved) within 30 days before baseline visit, except for influenza vaccine.The last anti-COVID vaccination was less than 4 months ago.SARS-CoV-2 infection occurred in less than 1 month ago.Pregnant or nursing women.Child-bearing potential and sexually active women who do not use highly effective birth control methods (oral contraceptives, intrauterine device, subcutaneous implant, transdermal patch used at least within 3 months) at the time of enrolment. Fertile and sexually active men not willing to strictly use (in all relationships) barrier methods of birth control throughout study. Those participants (both sexes) not sexually active can participate in the study if they are committed to avoid sexual intercourse throughout study (6 months).Chronic diseases that require use of immunosuppressive agents or immune response modulators (for instance: systemic corticosteroids, cyclosporine, rituximab, among others).Cancer under active chemotherapy treatment.Subjects with HIV infection history.Subjects with chronic renal or liver disease who have shown an infectious condition that required hospitalization or treatment with intravenous drugs within the last year prior baseline visit.