COVID-19REFORCO-BNCT05697705
Effectiveness of the Oxford-AstraZeneca COVID-19 Vaccine as a 2nd Booster, the REFORCO-Brazil Study
An observational study of COVID-19, run by AstraZeneca at 1 site in Brazil.
Trial summary
This study will address specific questions concerning the additional protection of the AZ COVID-19 vaccine as a second booster dose in preventing severe COVID-19 outcomes (hospitalisation, ICU admission etc) and will provide data to inform COVID-19 vaccine booster dose recommendations. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- COVID-19
- What is being tested?
- ChAdOx1 nCOV-19 vaccine (Vaxzeria), BNT162b2 (Pfizer) and Ad26.COV2.S (Janssen)
- Type of treatment
- Vaccines
- How many people
- 188,814,085 participants
- Where
- 1 siteBrazil
- Study dates
- 22 Jul 2022to 18 May 2023
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Population A is for evaluating second booster doses and will consist of individuals aged 18 years and over with immunocompromising conditions, healthcare workers aged 18 years and over, and individuals aged 50 years and over. Population B is for evaluating first booster doses and will consist of all individuals aged 18 and over.
Who may be able to join
- Hospitalized for SARS between 01 January 2022 and 31 December 2022 (Population A) or hospitalised for SARS between 01 August 2021 and 31 December 2022 (Population B).
- Eligible for a second COVID-19 vaccine booster dose at the time of SARS hospitalization (i.e., aged 50+ or aged 18+ and either a HCW or with an IC) for second booster objectives [Population A] OR eligible for a first COVID-19 vaccine booster dose at the time of SARS hospitalisation (i.e., aged 18+) for first booster objectives [Population B].
- Results available for a RT-PCR and/or antigen test for SARS-CoV-2 conducted on a sample taken up to 14 days after symptom onset.
- Individuals have required matching variables (e.g. age and sex).
Who cannot join
- Hospitalized for COVID-19 within 3 months prior to date of current hospital admission for SARS
- Nosocomially-acquired infection (where SARS case is flagged as nosocomial and/or where symptom onset date is after hospitalisation date)
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Real-world Effectiveness oF the OxfoRd-astrazeneca Covid-19 Vaccine as a Second bOoster Dose in Brazil (REFORCO-BRAZIL)
This study will address specific questions concerning the additional protection of the AZ COVID-19 vaccine as a second booster dose in preventing severe COVID-19 outcomes (hospitalisation, ICU admission etc) and will provide data to inform COVID-19 vaccine booster dose recommendations.
Read the detailed description
In Brazil, second COVID-19 boosters became available to specific risk groups in early 2022. By June 2022, immunocompromised individuals aged 12 years and above, individuals aged 50 years and above, and healthcare workers were eligible for a second booster. The vaccines available for second booster doses in Brazil are produced by AstraZeneca (AZ), Janssen, Pfizer and Sinovac.
While several studies have estimated absolute vaccine effectiveness (aVE) or relative vaccine effectiveness (rVE) of second boosters of mRNA COVID-19 vaccines, only a single study has, to date, estimated aVE of AZ vaccine as a second booster dose, and no studies have estimated rVE for AZ vaccine as a second booster dose. As the pandemic progresses, more individuals are choosing to become vaccinated (and boosted) against COVID-19 and thus there is greater need to evaluate the additional protection offered by a second booster dose amongst individuals previously administered a first booster. This is particularly important in the context of waning protection of a first booster dose.
The primary objective is to estimate relative vaccine effectiveness (rVE) against COVID-19 hospitalization of the AZ COVID-19 vaccine as a second booster dose relative to a first booster dose only, of any COVID-19 vaccine, administered at least four months ago.
This study will also evaluate rVE of other vaccines used in Brazil as a second booster doses. The study will further evaluate rVE of all vaccines (including the AZ-COVID-19 vaccine) as a first booster dose relative to a complete primary series only, of any COVID-19 vaccine administered at least four months ago."
- Conditions
- COVID-19
- Being tested
- ChAdOx1 nCOV-19 vaccine (Vaxzeria), BNT162b2 (Pfizer), Ad26.COV2.S (Janssen), CoronaVac (Sinovac)
- Keywords
- COVID-19, Real-World Effectiveness, ChAdOx1 nCOV-19 vaccine, Second booster dose
- Medical subject headings
- COVID-19
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ChAdOx1 nCOV-19 vaccine (Vaxzeria)Other
Used as 2nd booster, 1st booster, or primary series
BNT162b2 (Pfizer)Other
Used as 2nd booster, 1st booster, or primary series.
Ad26.COV2.S (Janssen)Other
Used as 2nd booster, 1st booster, or primary series.
CoronaVac (Sinovac)Other
Used as 2nd booster, 1st booster, or primary series.
| Study group | Role | What they receive |
|---|---|---|
| Population A | For evaluating second booster doses Receives: Other: ChAdOx1 nCOV-19 vaccine (Vaxzeria); Other: BNT162b2 (Pfizer); Other: Ad26.COV2.S (Janssen); Other: CoronaVac (Sinovac) | |
| Population B | For evaluating first booster doses Receives: Other: ChAdOx1 nCOV-19 vaccine (Vaxzeria); Other: BNT162b2 (Pfizer); Other: Ad26.COV2.S (Janssen); Other: CoronaVac (Sinovac) |
What is being measured
The primary outcome is the main question the study is designed to answer.
COVID-19 confirmed by a positive antigen test or RT-PCR test in an individual hospitalized for SARS
Study includes SARS hospitalizations between August 2021 and December 2022 for evaluation of 1st booster dose effectiveness, and SARS hospitalizations between January 2022 and December 2022 for evaluation of 2nd booster dose effectiveness.
Measured: Sample date within 14 days prior to and up to 2 days after hospitalization.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Jan 2023
- Study start22 Jul 2022
- Primary completion18 May 2023
- Study completion18 May 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for COVID-19Studies of the same condition, open and under way.
- More trials run by AstraZenecaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Retrospective
- Enrolment
- 188,814,085 participants (actual)
Sponsor and investigators
- Lead sponsor
- AstraZeneca
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05697705
- Sponsor's protocol ID
- D8111R00028
- Acronym
- REFORCO-B
- Status last verified
- Nov 2024
- First submitted
- 23 Jan 2023
- Last updated
- 21 Nov 2024
- Results posted
- No
- FDA-regulated drug
- No
Publications
Meeraus W, Postema A, Gray CM, Lee A, Maria AS, Furtado BE, Conde-Sousa E, Ouwens M, Valverde DA, da Cunha CA, Barbosa AN, Corte C, Taylor S. Second booster doses of adenoviral- and mRNA-based COVID-19 vaccines increase protection against COVID-19 hospitalization: Final analysis from the REFORCO-Brazil real-world effectiveness study during Omicron. Vaccine. 2025 Apr 19;53:126955. doi: 10.1016/j.vaccine.2025.126955. Epub 2025 Mar 10.
PubMed 40068393
Study at a glance
From the registry record, last updated by the sponsor on 21 Nov 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Real-world Effectiveness oF the OxfoRd-astrazeneca Covid-19 Vaccine as a Second bOoster Dose in Brazil (REFORCO-BRAZIL)
- ClinicalTrials.gov ID
- NCT05697705
- Acronym / sponsor ID
- REFORCO-B / D8111R00028
- Conditions
- COVID-19
- Keywords
- COVID-19, Real-World Effectiveness, ChAdOx1 nCOV-19 vaccine, Second booster dose
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 188,814,085 participants (actual)
- Lead sponsor
- AstraZenecaIndustry (pharma, biotech, devices)
- Study start
- 22 Jul 2022 (actual)
- Primary completion
- 18 May 2023 (actual)
- Study completion
- 18 May 2023 (actual)
- First posted
- 26 Jan 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study will address specific questions concerning the additional protection of the AZ COVID-19 vaccine as a second booster dose in preventing severe COVID-19 outcomes (hospitalisation, ICU admission etc) and will provide data to inform COVID-19 vaccine booster dose recommendations.
Detailed description
In Brazil, second COVID-19 boosters became available to specific risk groups in early 2022. By June 2022, immunocompromised individuals aged 12 years and above, individuals aged 50 years and above, and healthcare workers were eligible for a second booster. The vaccines available for second booster doses in Brazil are produced by AstraZeneca (AZ), Janssen, Pfizer and Sinovac.
While several studies have estimated absolute vaccine effectiveness (aVE) or relative vaccine effectiveness (rVE) of second boosters of mRNA COVID-19 vaccines, only a single study has, to date, estimated aVE of AZ vaccine as a second booster dose, and no studies have estimated rVE for AZ vaccine as a second booster dose. As the pandemic progresses, more individuals are choosing to become vaccinated (and boosted) against COVID-19 and thus there is greater need to evaluate the additional protection offered by a second booster dose amongst individuals previously administered a first booster. This is particularly important in the context of waning protection of a first booster dose.
The primary objective is to estimate relative vaccine effectiveness (rVE) against COVID-19 hospitalization of the AZ COVID-19 vaccine as a second booster dose relative to a first booster dose only, of any COVID-19 vaccine, administered at least four months ago.
This study will also evaluate rVE of other vaccines used in Brazil as a second booster doses. The study will further evaluate rVE of all vaccines (including the AZ-COVID-19 vaccine) as a first booster dose relative to a complete primary series only, of any COVID-19 vaccine administered at least four months ago."
Study design
- Observational model
- Case-control
- Time perspective
- Retrospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Population A | – | Other: ChAdOx1 nCOV-19 vaccine (Vaxzeria), Other: BNT162b2 (Pfizer), Other: Ad26.COV2.S (Janssen), Other: CoronaVac (Sinovac)For evaluating second booster doses |
| Population B | – | Other: ChAdOx1 nCOV-19 vaccine (Vaxzeria), Other: BNT162b2 (Pfizer), Other: Ad26.COV2.S (Janssen), Other: CoronaVac (Sinovac)For evaluating first booster doses |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Population A is for evaluating second booster doses and will consist of individuals aged 18 years and over with immunocompromising conditions, healthcare workers aged 18 years and over, and individuals aged 50 years and over. Population B is for evaluating first booster doses and will consist of all individuals aged 18 and over.
Key inclusion criteria (4 listed)
- Hospitalized for SARS between 01 January 2022 and 31 December 2022 (Population A) or hospitalised for SARS between 01 August 2021 and 31 December 2022 (Population B).
- Eligible for a second COVID-19 vaccine booster dose at the time of SARS hospitalization (i.e., aged 50+ or aged 18+ and either a HCW or with an IC) for second booster objectives [Population A] OR eligible for a first COVID-19 vaccine booster dose at the time of SARS hospitalisation (i.e., aged 18+) for first booster objectives [Population B].
- Results available for a RT-PCR and/or antigen test for SARS-CoV-2 conducted on a sample taken up to 14 days after symptom onset.
- Individuals have required matching variables (e.g. age and sex).
Key exclusion criteria (2 listed)
- Hospitalized for COVID-19 within 3 months prior to date of current hospital admission for SARS
- Nosocomially-acquired infection (where SARS case is flagged as nosocomial and/or where symptom onset date is after hospitalisation date)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ChAdOx1 nCOV-19 vaccine (Vaxzeria)Used as 2nd booster, 1st booster, or primary series | Other | Population A, Population B |
| BNT162b2 (Pfizer)Used as 2nd booster, 1st booster, or primary series. | Other | Population A, Population B |
| Ad26.COV2.S (Janssen)Used as 2nd booster, 1st booster, or primary series. | Other | Population A, Population B |
| CoronaVac (Sinovac)Used as 2nd booster, 1st booster, or primary series. | Other | Population A, Population B |
Primary outcome
COVID-19 confirmed by a positive antigen test or RT-PCR test in an individual hospitalized for SARS
Time frame: Sample date within 14 days prior to and up to 2 days after hospitalization.
Study includes SARS hospitalizations between August 2021 and December 2022 for evaluation of 1st booster dose effectiveness, and SARS hospitalizations between January 2022 and December 2022 for evaluation of 2nd booster dose effectiveness.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 21 Nov 2024.
- Derived from this study: PubMed 40068393Meeraus W, Postema A, Gray CM, Lee A, Maria AS, Furtado BE, Conde-Sousa E, Ouwens M, Valverde DA, da Cunha CA, Barbosa AN, Corte C, Taylor S. Second booster doses of adenoviral- and mRNA-based COVID-19 vaccines increase protection against COVID-19 hospitalization: Final analysis from the REFORCO-Brazil real-world effectiveness study during Omicron. Vaccine. 2025 Apr 19;53:126955. doi: 10.1016/j.vaccine.2025.126955. Epub 2025 Mar 10.
- Redacted CSR SynopsisLink provided by the sponsor.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of COVID-19, run by AstraZeneca at 1 site in Brazil.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 21 Nov 2024. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Brazil. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
COVID-19 confirmed by a positive antigen test or RT-PCR test in an individual hospitalized for SARS (time frame: Sample date within 14 days prior to and up to 2 days after hospitalization.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05697705, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Nov 2024.