Immunogenicity Characterization of COVID-19 Vaccines: A Systematic Review and Meta-analysis

Introduction: Immunogenicity has emerged as a challenge in the development of vaccines against coronavirus disease of 2019 (COVID-19). Immunogenicity is a determinant of the efficacy and safety of vaccines. This systematic review and associated meta-analysis summarized and characterized the immunogenicity of COVID-19 vaccines in randomized controlled trials (RCTs). Methods: Relevant RCTs were systematically sourced from different medical databases in August 2021. The risk ratios and mean differences with 95% confidence intervals were calculated. Results: Of 2,310 papers, 16 RCTs were eligible for review. These RCTs involved a total of 26,698 participants (15,292 males and 11,231 females). The pooled results showed a significant difference in the geometric mean titer between the vaccinated and control groups in favor of the vaccine group after 1 and 2 months of follow-up, for the young age group (18 -< 55y), and with different doses (P < 0.001). The difference in the older age group (>55y) was insignificant (P = 0.24). The seroconversion rate of spike neutralizing antibodies favored the vaccine groups 1 or 2 months after vaccination (P < 0.001). The seroconversion rate of the vaccine group was significantly different (P < 0.001) from that of the control group. Conclusions: Vaccination elicits immunogenicity in the follow-up period for all age groups and at low and large doses. Therefore, people should be encouraged to receive vaccines currently being offered. A boost dose has been asserted for the elderly.

SARS-CoV-2-neutralising antibody BGB-DXP593 in mild-to-moderate COVID-19: a multicentre, randomised, double-blind, phase 2 trial.

Background: BGB-DXP593, a neutralising monoclonal antibody against SARS-CoV-2, has demonstrated strong activity in reducing viral RNA copy number in SARS-CoV-2-infected animal models. We aimed to examine the efficacy and safety of BGB-DXP593 in ambulatory patients with mild-to-moderate COVID-19. Methods: This global, randomised, double-blind, phase 2 study (ClinicalTrials.govNCT04551898) screened patients from 20 sites in Australia, Brazil, Mexico, South Africa, and the USA from December 2, 2020, through January 25, 2021. Patients with a first-positive SARS-CoV-2 test (positive reverse transcription-polymerase chain reaction test or authorised antigen test) ≤3 days before screening and mild-to-moderate COVID-19 symptoms for ≤7 days before treatment were randomised 1:1:1:1 to receive a single intravenous infusion of BGB-DXP593 5, 15, or 30 mg/kg, or placebo. The primary endpoint was change from baseline to Day 8 in viral RNA copies/mL as measured in nasopharyngeal swabs. Secondary endpoints were hospitalisation rate due to worsening COVID-19 and treatment-emergent adverse events (TEAEs). A prespecified exploratory endpoint was change in viral RNA copy number in saliva. Findings: Relative to the natural rate of clearance as assessed in placebo-exposed patients (-3.12 log10 copies/mL), no significant differences in nasopharygneal viral RNA copy number changes were observed (-2.93 to -3.63 log10 copies/mL) by Day 8 in BGB-DXP593-treated patients. Reductions from baseline to Day 8 in saliva viral RNA copy number were larger with BGB-DXP593 5 mg/kg (-1.37 log10 copies/mL [90% confidence interval -2.14, -0.61]; nominal p = 0.003) and 15 mg/kg (-1.26 [-2.06, -0.46]; nominal p = 0.01) vs placebo, and differences favoring BGB-DXP593 were observed by Day 3, although not statistically significant; no difference from placebo was observed for BGB-DXP593 30 mg/kg (-0.71 [-1.45, 0.04]; nominal p = 0.12). Hospitalisation rate due to COVID-19 was numerically lower with BGB-DXP593 (pooled: 2/134 patients; 1.5%) vs placebo (2/47 patients; 4.3%), although not statistically significant. Incidence of TEAEs was similar across treatment groups. No TEAE led to treatment discontinuation. Five serious TEAEs occurred, all attributed to COVID-19 pneumonia. Interpretation: BGB-DXP593 was well tolerated. Although nasopharyngeal swab SARS-CoV-2 viral RNA copy number was not significantly decreased compared with placebo, viral RNA copy number was inconsistently reduced by Day 8 in saliva at some doses as low as 5 mg/kg. Funding: BeiGene, Ltd.

Randomized, Double-Blinded, Placebo-Controlled Phase 2 Trial of an Inactivated Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine in Healthy Adults.

BACKGROUND: We evaluated an inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine for immunogenicity and safety in adults aged 18-59 years. METHODS: In this randomized, double-blinded, controlled trial, healthy adults received a medium dose (MD) or a high dose (HD) of the vaccine at an interval of either 14 days or 28 days. Neutralizing antibody (NAb) and anti-S and anti-N antibodies were detected at different times, and adverse reactions were monitored for 28 days after full immunization. RESULTS: A total of 742 adults were enrolled in the immunogenicity and safety analysis. Among subjects in the 0, 14 procedure, the seroconversion rates of NAb in MD and HD groups were 89% and 96% with geometric mean titers (GMTs) of 23 and 30, respectively, at day 14 and 92% and 96% with GMTs of 19 and 21, respectively, at day 28 after immunization. Anti-S antibodies had GMTs of 1883 and 2370 in the MD group and 2295 and 2432 in the HD group. Anti-N antibodies had GMTs of 387 and 434 in the MD group and 342 and 380 in the HD group. Among subjects in the 0, 28 procedure, seroconversion rates for NAb at both doses were both 95% with GMTs of 19 at day 28 after immunization. Anti-S antibodies had GMTs of 937 and 929 for the MD and HD groups, and anti-N antibodies had GMTs of 570 and 494 for the MD and HD groups, respectively. No serious adverse events were observed during the study period. CONCLUSIONS: Adults vaccinated with inactivated SARS-CoV-2 vaccine had NAb as well as anti-S/N antibody and had a low rate of adverse reactions. CLINICAL TRIALS REGISTRATION: NCT04412538.

A phase 2, open label, multicenter, single arm study of tocilizumab on the efficacy and tolerability of tocilizumab in the treatment of patients with COVID-19 pneumonia (TOCIVID-19 trial): Statistical analysis plan.

BACKGROUND: Tocilizumab, an IL-6 receptor antagonist, was suggested as a possible treatment of severe or critical COVID-19 pneumonia in a small Chinese study. The TOCIVID-19 trial evaluates efficacy and tolerability of tocilizumab in the treatment of patients with severe or critical COVID-19 pneumonia. METHODS: TOCIVID-19 is an academic multicenter, single-arm, open-label, phase 2 study. All the patients are being offered a single shot of 8 mg/kg of Tocilizumab (up to a maximum of 800 mg), with an eventual second administration at the discretion of the Investigator. A companion prospective cohort, added to corroborate internal validity, includes either patients not eligible for phase 2 or subjects eligible for phase 2 but exceeding the planned sample size. 14- and 30-days lethality rates are the two co-primary endpoints in the intention-to-treat (ITT) population. Secondary objectives are to evaluate mortality and clinical improvement in the modified-ITT population of subjects who received the drug. Details of the methodological and statistical approaches are reported here reflecting the amendments impelled by the continuously increasing knowledge on COVID-19 progression and challenges in data collection. CONCLUSION: This paper provides details of planned statistical analyses for TOCIVID19 trial to reduce the risk of reporting bias and increase validity of the study findings.TOCIVID-19 trial is registered in the EudraCT database with number 2020-001110-38 and in clinicaltrials.gov with ID NCT04317092.