EFFECTIVENESS, SAFETY AND IMMUNOGENICITY OF THE HALF DOSE OF THE VACCINE ChadOx1 nCoV-19 (AZD1222) for COVID-19

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

UNKNOWN

Clinical Phase

PHASE2/PHASE3

Total Enrollment

29637 participants

Study Classification

INTERVENTIONAL

Study Start Date

2021-06-01

Study Completion Date

2022-10-30

Brief Summary

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This study is clinical trial (intervention study with external comparison group) to test vaccination with reduced dose (half dose) of ChAdOx1 nCoV-19 (AZD1222), in a 2-dose schedule with an interval of 8 weeks, including all adults aged 18 to 49 years from Viana city - Espírito Santo (ES)/Brazil, on the incidence of new cases over 12 months following treatment, compared to an external group from same state and adjusted for socio-demographic and epidemiological variables.

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Detailed Description

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This study is clinical trial (intervention study with external comparison group) to test vaccination with reduced dose (half dose) of ChAdOx1 nCoV-19 (AZD1222), in a 2-dose schedule with an interval of 8 weeks, including all adults aged 18 to 49 years from Viana city - Espírito Santo (ES)/Brazil, on the incidence of new cases over 12 months following treatment, compared to an external group from same state and adjusted for socio-demographic and epidemiological variables. Cellular and humoral immunity will be studied in a representative sub-sample compared to an external reference group (cohort of health workers) vaccinated with standard dose. The outcomes will be evaluated at 28 days after the second dose and follow-up after 6 months and 12 months. The main outcome will be to decrease in 60% the incidence of new cases over 6 months after receiving the vaccine. The clinical epidemiological variables will be obtained from e-SUS VS, e-SUS notifica and datasus: number of cases, number of deaths with specific ICD for covid-19, number of hospital admissions for covid-19; number of ICU admissions for the treatment of SARS, total number of tests (RT-PCR) performed and positive. The cellular and humoral immune response will be assessed by viral neutralization assay (neutralizing antibody test), serological assay by chemiluminescence, determination of specific IgM and IgG profiles, measurement of systemic soluble factors (chemokines, cytokines and growth factors), stimulation antigen-specific peripheral blood mononuclear cells in vitro and investigation of memory T and B lymphocytes and intracytoplasmic cytokines. It is estimated to include 29,637 people in the study, to reach 85% vaccination cover of individuals aged 18-49 years. The subsample size immunogenicity test is 600 individuals from the eligible population, estimating losses of 15% and study power of 90%, alpha error of 1%. The hypothesis of the study is that the reduction in the incidence of covid-19 and the cellular and humoral immune response achieved with a half dose will be similar to the reduction expected with the standard dose.

Conditions

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SARS-CoV-2

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

SEQUENTIAL

Primary Study Purpose

PREVENTION

Blinding Strategy

NONE

Study Groups

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Group 1

Half dose of ChAdOx1 nCoV-19 (AZD1222) ) in a 2-dose schedule with an interval of 8 weeks.

Group Type EXPERIMENTAL

Half dose of ChAdOx1 nCoV-19 (AZD1222)

Intervention Type BIOLOGICAL

Vaccination with reduced dose (half dose) of ChAdOx1 nCoV-19 (AZD1222), in a 2-dose schedule with an interval of 8 weeks, including all adults aged 18 to 49 years, from non-priority groups, from Viana city - Espírito Santo (ES)/Brazil.

Group 2

Standad dose of ChAdOx1 nCoV-19 (AZD1222) in a 2-dose schedule with an interval of 8 weeks.

Group Type ACTIVE_COMPARATOR

Standard dose of ChAdOx1 nCoV-19 (AZD1222)

Intervention Type BIOLOGICAL

Vaccination with standad dose of ChAdOx1 nCoV-19 (AZD1222), in a 2-dose schedule with an interval of 8 weeks, in external cohort of health workers aged 18 to 49 years.

Interventions

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Half dose of ChAdOx1 nCoV-19 (AZD1222)

Vaccination with reduced dose (half dose) of ChAdOx1 nCoV-19 (AZD1222), in a 2-dose schedule with an interval of 8 weeks, including all adults aged 18 to 49 years, from non-priority groups, from Viana city - Espírito Santo (ES)/Brazil.

Intervention Type BIOLOGICAL

Standard dose of ChAdOx1 nCoV-19 (AZD1222)

Vaccination with standad dose of ChAdOx1 nCoV-19 (AZD1222), in a 2-dose schedule with an interval of 8 weeks, in external cohort of health workers aged 18 to 49 years.

Intervention Type BIOLOGICAL

Eligibility Criteria

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Inclusion Criteria

\- residents of Viana, Espírito Santo, aged between 18 and 49 years

Exclusion Criteria

* Pregnant women;
* History of severe allergic reaction (anaphylaxis) to any previously administered vaccine;
* Having received another vaccine in the last 14 days;
* Belonging to a priority risk group for vaccination, as per the PNI recommendations;
* Have fever or flu-like symptoms;
* Have previously received any vaccine for covid-19 at any time;
* Recent diagnosis of covid-19 with onset of symptoms 28 days before vaccination;
* Disorders of coagulation and use of anticoagulants.

Minimum Eligible Age

18 Years

Maximum Eligible Age

49 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes