Dataset Information

Immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2 with 12-dose vials: An interim analysis.

ABSTRACT:

Background

ChAdOx1 nCoV-19 (AZD 1222) is the main vaccine planned for general administration in Thailand. This vaccine is stored in multiple-dose vials meant to be administered to 10 recipients with a volume of 0.5 mL for each dose. However, the vaccine vials were overfilled, which allows the administration of more than 10 doses per vial. We have stipulated the preparation and use of ChAdOx1 nCoV-19 vaccine using traditional 21 or 25G needles and planned to investigate the immune responses of participants who were administered the ChAdOx1 nCoV-19 vaccine using this technique.

Methods

We measured anti-SARS-CoV-2 anti-spike RBD IgG and neutralising antibody using a surrogate virus neutralising test (sVNT) among adults aged 18-72 years on average of 8.57 weeks (IQR 6.85-8.93) after the first dose of ChAdOx1 nCoV-19 vaccine. The primary outcome was the antibody level. The secondary outcomes included adverse events, factors affecting antibody levels, and incidence of COVID-19 infection.

Findings

In all, 60 participants comprised 25 males and 35 females. The mean age was 53.70 ± 17.48 years. BMI was 23.45 ± 3.69 kg/m². Tests for the neutralising antibody were positive in 60% of the participants (71.4% among males and 44% among females). The median anti-SARS-CoV-2 QuantiVac (anti-spike IgG) level among male and female samples was 111.83 BAU/mL (IQR 73.48-196.74 BAU/mL) and 159.65 BAU/mL (IQR 100.39-371.81), respectively. The positive QuantiVac value of male and female samples was 88.00% and 98.44%, respectively (p-value = 0.382) .A good correlation was observed between neutralising Ab and anti-spike RBD IgG.

Conclusion

Patients receiving 12-dose per vial injections of ChAdOx1 nCoV-19 exhibited high levels of immunity without severe side effects. This technique can be adopted to maximise the number of doses per vial while preserving vaccine effectiveness.

SUBMITTER: Manomaipiboon A

PROVIDER: S-EPMC8692062 | biostudies-literature |

REPOSITORIES: biostudies-literature

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