Effectiveness, safety, and immunogenicity of half dose ChAdOx1 nCoV-19 COVID-19 Vaccine: Viana project

• DOI: 10.3389/fimmu.2022.966416
• Publication Date: 2022-10-31T17:28:51Z
• Authors: Valéria Valim; Olindo Assis Mart...; Maria da Penha Go...; Luiz Antônio Bast...; Daniel Antunes Ma...; Sheila Maria Barb...; Adriana Souza Aze...; Lauro Ferreira Pi...; Carla Magda Allan...; Nésio Fernandes d...; Isac Ribeiro Moulaz; Laiza Hombre Dias; Samira Tatiyama M...; Andréa Teixeira-C...; José Geraldo Mill
• Keywords: Seroconversion

Fractional dose is an important strategy to increase access vaccines. This study evaluated the effectiveness, safety, and immunogenicity of half ChAdOx1 nCoV-19 vaccine. A non-inferiority non-randomized controlled trial compared a with full dose, interval 8 10 weeks, in individuals aged 18–49 years. The primary endpoints were incidence rate new cases/1,000 person-year at 90 days after 14 second confirmed by RT-PCR cases registered SUS National Health Surveillance Database (e-SUS VS). anti-SARS-CoV-2 spike (S) protein receptor binding domain (RBD) chemiluminescence neutralizing antibodies plaque reduction neutralization test (PRNT) titrated. soluble biomarkers quantified multiplex immunoassay. Follow-up was dose. total 29,598 vaccinated. After exclusion, 16,570 who received 6,402 doses analyzed. non-inferior (23.7 vs. 25.7 per 1,000 persons-year [coefficient group -0.09 CI95%(-0.49 0.31)], even adjusting for age sex. There no deaths or hospitalization immunization either group. Immunogenicity subsample (N=558) 154 healthcare workers seroconversion seronegative baseline 99.8%, similar that (100%). Geometric mean concentration (95% CI; BAU/mL) = 188 (163-217) 529 (423–663) (p < 0.001). In seropositive subjects (pre-immune individuals), first induced very high IgG-S 1,359 (1,245-1,483) 1,354 (1,048–1,749) BAU/mL. plasma chemokines, pro-inflammatory/regulatory cytokines, growth factors. frequency adverse events similar. No serious reported. as effective, safe, immunogenic immune response pre-immune (seropositive baseline) indicates may be booster schedule.