An Evaluation of the Safety and Immunogenicity of MVC-COV1901: Results of an interim analysis of a phase III, parallel group, randomized, double-blind, active-controlled study

BackgroundData from previous studies of the MVC-COV1901 vaccine, a subunit vaccine against SARS-CoV-2 based on the stable prefusion spike protein (S-2P) adjuvanted with CpG 1018 adjuvant and aluminum hydroxide, suggest that the vaccine is generally safe and elicits a good immune response in healthy adults and adolescents. By comparing with AZD1222, this study adds to the findings from previous trials and further evaluates the breadth of protection offered by MVC-COV1901. MethodsIn this phase 3, parallel group, randomized, double-blind, active-controlled trial conducted in 2 sites in Paraguay, we assigned adults aged 18 to 91 years in a 1:1 ratio to receive intramuscular doses of MVC-COV1901 or AZD1222 administered as scheduled in the clinical trial. Serum samples were collected on the day of vaccination and 14 days after the second dose. Primary and secondary safety and immunogenicity endpoints were assessed. In addition, other outcomes investigated were cross-reactive immunity against the Omicron strain and the induction of IgG subclasses. ResultsA total of 1,030 participants underwent randomization. Safety data was derived from this set while primary immunogenicity data involved a per-protocol immunogenicity (PPI) subset including 225 participants. Among the participants, 58% are seropositive at baseline. When compared against AZD1222, MVC-COV1901 exhibited superiority in terms of neutralizing antibody titers and non-inferiority in terms of seroconversion rates. Reactogenicity was generally mild and no serious adverse event was attributable to MVC-COV1901. Both vaccines have a Th1-biased response predominated by the production of IgG1 and IgG3 subclasses. Omicron-neutralizing titers were 44.5 times lower compared to wildtype-neutralizing titers among seronegative individuals at baseline. This fold-reduction was 3.0 times among the seropositive. ConclusionResults presented here demonstrate the safe and robust immunogenicity from MVC-COV1901. Previous infection coupled with vaccination of this vaccine may offer protection against the Omicron strain though its durability is still unknown. ClinicalTrials.gov registrationNCT05011526

An Immunobridging study to evaluate the neutralizing antibody titer in adults immunized with two doses of either ChAdOx1-nCov-19 (AstraZeneca) or MVC-COV1901.

BackgroundRapid development and deployment of vaccine is crucial to control the continuously evolving COVID-19 pandemic. Placebo-controlled phase 3 efficacy trial is still standard for authorizing vaccines in majority of the world. However, due to lack of cases or participants in parts of the world, this has not always been feasible. An alternative to efficacy trial is immunobridging, in which the immune response or correlates of protection of a vaccine candidate is compared against an approved vaccine. Here we describe a case study where our candidate vaccine, MVC-COV1901, has been granted for emergency use authorization (EUA) locally based on the non-inferiority immunobridging process. MethodsThe per protocol immunogenicity (PPI) subset from the MVC-COV1901 phase 2 trial was used for this study and consisted of 903 subjects who have received two doses of MVC-COV1901 as scheduled in the clinical trial. The comparator set of population consisted of 200 subjects of [≥] 20 years of age who were generally healthy and have received two doses of AstraZeneca ChAdOx nCOV-19 (AZD1222) recruited from Taoyuan General Hospital, Ministry of Health and Welfare. ResultsMVC-COV1901 was shown to have a geometric mean titer (GMT) ratio lower bound 95% confidence interval (CI) of 3.4 against the comparator vaccine and a seroconversion rate of 95.5% at the 95% CI lower bound, which both exceeded the criteria set by the Taiwan regulatory authority for EUA approval. These results supported the EUA approval of MVC-COV1901 by the Taiwanese regulatory authority in July 2021. Following the consensus of the International Coalition of Medicines Regulatory Authorities (ICMRA), countries from the Access Consortium has recently adopted the use of immunobridging studies as acceptable for authorizing COVID-19 vaccines in lieu of efficacy data. ConclusionThe data presented in the study showed that it is reasonably likely that the vaccine efficacy of MVC-COV1901 is similar or superior to that of AZ. Data could be used in support of further vaccine development and regulatory approval.

Safety and Immunogenicity of SARS-CoV-2 S-2P Protein Vaccine MVC-COV1901 in People Living with HIV

ObjectivesTo provide data on the immune response to COVID-19 vaccines in people living with HIV (PWH), MVC-COV1901, a recombinant protein vaccine containing S-2P protein adjuvanted with CpG 1018 and aluminium hydroxide, was assessed. MethodsA total of 57 PWH of [≥] 20 years of age who are on stable antiretroviral therapy and with CD4+ T cell [≥] 350 cells/mm3 and HIV viral load < 103 copies/ml were compared with 882 HIV-negative participants. Participants received 2 doses of MVC-COV1901 28 days apart. Safety and the immunogenicity were evaluated. ResultsNo vaccine-related serious adverse events (SAEs) were recorded. Seroconversion rates (SCRs) of 100% and 99.8% were achieved in people living with HIV (PWH) and comparators, respectively, 28 days after second dose. The geometric mean titers (GMTs) (95% confidence interval [CI]) against wild type SARS-CoV-2 virus were 136.62 IU/mL (WHO Standardized International Unit) (95% CI 114.3-163.3) and 440.41 IU/mL (95% CI 421.3-460.4), for PWH and control groups, respectively, after adjusting for sex, age, BMI category, and comorbidity, and the adjusted GMT ratio of comparator/PWH was 3.22 (95% CI 2.6-4.1). A higher CD4/CD8 ratio was associated with a higher GMT (R=0.27, p=0.039). ConclusionsMVC-COV1901 has shown robust safety but weaker immunogenicity responses in PWH. As a result, a third dose or booster doses of MVC-COV1901 may be appropriate for PWH.