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SSRN; 2022.
Preprint in English | SSRN | ID: ppcovidwho-331858


Background: Waning of neutralizing titers and decline of protection shorter after the second dose of COVID-19 vaccines was observed, including China-made inactivated vaccines. Efficacy of a heterologous boosting using one dose recombinant SARS-CoV-2 fusion protein vaccine (V-01) in inactivated vaccine-primed population was studied, aimed to restore the immunity. Methods: A randomized, double-blind and placebo-controlled phase Ⅲ trial was conducted in healthy people aged 18 years or older in Pakistan and Malaysia. Each eligible participant received one dose of V-01 vaccine developed by Livzon Mabpharm Inc . or placebo 3-6 months after the 2-dose primary regimen, and was monitored for safety and efficacy. The primary endpoint was protection against confirmed symptomatic SARS-CoV-2 infection. Results: A total of 10,218 participants were randomly assigned to receive vaccine or placebo. Virus-neutralizing antibodies were assessed in 419 participants. A dramatical increase (11.3-fold;128.3 to 1452.8) of neutralizing titers was measured in V-01 group at 14 days after the booster. Over the two months surveillance, vaccine efficacy was 47.8% (95%CI: 22.6 to 64.7) according to the intention-to-treat principle. The most common adverse events were transient, mild-to-moderate pain at the injection site, fever, headache, and fatigue. Serious adverse events occurred almost equally in V-01 (0.12%) and placebo (0.16%) groups. Conclusion: The heterologous boosting with V-01 vaccine was safe, efficacious, and could elicit robust humoral immunity under the epidemic of the Omicron variant.

Vaccine ; 39(20): 2746-2754, 2021 05 12.
Article in English | MEDLINE | ID: covidwho-1174522


BACKGROUND: This study examined the safety and immunogenicity of an inactivated SARS-CoV-2 vaccine. METHOD: In a phase I randomized, double-blinded, placebo-controlled trial involving 192 healthy adults 18-59 years old, two injections of three doses (50 EU, 100 EU, 150 EU) of an inactivated SARS-CoV-2 vaccine or placebo were administered intramuscularly at a 2- or 4-week interval. The safety and immunogenicity of the vaccine were evaluated. RESULTS: Vaccination was completed in 191 subjects. Forty-four adverse reactions occurred within 28 days, most commonly mild pain and redness at the injection site or slight fatigue. At days 14 and 28, the seroconversion rates were 87.5% and 79.2% (50 EU), 100% and 95.8% (100 EU), and 95.8% and 87.5% (150 EU), respectively, with geometric mean titers (GMTs) of 18.1 and 10.6, 54.5 and 15.4, and 37.1 and 18.5, respectively, for the schedules with 2-week and 4-week intervals. Seroconversion was associated with synchronous upregulation of antibodies against the S protein, N protein and virion and a cytotoxic T lymphocyte (CTL) response. No cytokines and immune cells related to immunopathology were observed. Transcriptome analysis revealed the genetic diversity of immune responses induced by the vaccine. INTERPRETATION: In a population aged 18-59 years in this trial, this inactivated SARS-CoV-2 vaccine was safe and immunogenic. TRIAL REGISTRATION: CTR20200943 and NCT04412538.

COVID-19 Vaccines , COVID-19 , Vaccines , Adolescent , Adult , Antibodies, Viral , China , Double-Blind Method , Humans , Immunogenicity, Vaccine , Middle Aged , SARS-CoV-2 , Young Adult
Hum Vaccin Immunother ; 17(3): 656-660, 2021 03 04.
Article in English | MEDLINE | ID: covidwho-801738


COVID-19 has become a global pandemic, and an effective vaccine is needed. During the outbreak, the urgency for developing candidate vaccines has brought distinct challenges to clinical development. An efficacy trial, which measures whether the vaccine reduces the incidence of disease, is ordinarily required to fully evaluate vaccine efficacy. However, emergency use may be possible if promising immunogenicity results are observed. A ring vaccination trial, which recruits subjects connected to a known case either socially or geographically, is a solution to evaluate vaccine efficacy and control the spread of the disease simultaneously although its conduct is challenging. Nevertheless, when COVID-19 becomes a recurrent epidemic, an 'individual-level' efficacy trial is preferred. Innovative statistical designs, including seamless design, platform trial, master protocol design, are helpful to accelerate clinical development. A seamless Phase I/II design has been applied in multiple COVID-19 vaccine studies to date. However, Phase II/III design should be done very carefully. The control of type I error, maintaining trial blinding and statistical methods leading to unbiased estimates should be pre-specified in the clinical protocol. A Data Safety Monitoring Board is especially important, given the need to assure an adequate level of safety when society want a safe and effective vaccine.

COVID-19 Vaccines/immunology , COVID-19/immunology , COVID-19/prevention & control , Clinical Trials as Topic , Humans , Immunogenicity, Vaccine/immunology , Pandemics/prevention & control , Research Design , SARS-CoV-2/immunology