Effectiveness of Vaccination Against COVID-19 in Brazil: Case-Control Study

Study Overview
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Brief Summary
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The main objective of the study is to evaluate the effectiveness of the vaccine against covid-19, recommended by the national immunization program. This is a multicentric, observational, case-control study. Participants Cases with the disease will be compared to Control Participants, that is, without the disease, regarding the vaccination history for Covid-19.Complementarily, an evaluation of cellular and humoral immunity will be carried out in a sample of both case and control participants, taking into account the vaccination history.

Official Title
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Effectiveness of Vaccination Against COVID-19 in Brazil: Case-Control Study

Conditions
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COVID-19 Vaccines

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Agreement to participate in the study after reading, understanding and signing the informed consent. Availability and possibility of being followed up during the follow-up period defined in the study, through visits to research centers, home visits, telephone contacts or other means of digital communication. Completing the case or control definitions described below. Exclusion Criteria: Behavioral, cognitive or psychiatric illness that, in the opinion of the responsible investigator or his/her medical representative, affects the participant's ability to understand and comply with the requirements of the study protocol; Any other condition that, in the opinion of the responsible investigator or his/her medical representative, may jeopardize the safety or rights of a potential participant or prevent him/her from complying with this protocol.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Case<br>Individuals aged 18 years or older, with a suspected clinical picture of COVID-19 virologically confirmed, that is, with positive RT-PCR for SARS-CoV-2 in a respiratory secretion sample collected in the first 7 days of the onset of symptoms , who did not have a positive RT-PCR result for SARS-CoV-2 in the 90 days preceding enrollment in the study. | |
| Control<br>Individuals residing in the vicinity of the case, aged 18 years or older, without a suspected clinical picture of COVID-19 and with RT-PCR negative for SARS-CoV-2 in a respiratory secretion sample collected at the time of inclusion, followed by confirmation of the absence of signs and symptoms suggestive of COVID-19 within the next 7 days. | |
| immunogenicity analyzes<br>a convenience sample composed of all cases exposed or not to vaccination and 200 controls, 100 vaccinated and 100 unvaccinated, for analysis of humoral response. | |
| assessment of cellular immunity<br>a sample of 100 vaccinated cases and 100 unvaccinated cases followed prospectively, and 100 vaccinated controls 100 unvaccinated controls assessed spot-on at enrollment. | |
| analysis of potential genetic risk factors for the occurrence of severe forms of COVID-19 (SRAG)<br>a total of 50 cases | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Evaluate the effectiveness of the vaccination against COVID-19. | confirmed disease (RT-PCR positive for SARS-CoV-2), according to the clinical spectrum (of mild disease , moderate to severe) and outcome (disease-related death). | 12 months | 
| Evaluate the effectiveness of the vaccination against COVID-19. | according to the vaccine used, the number of doses and the interval from the last dose to the onset of symptoms. | 12 months | 
| Evaluate the effectiveness of the vaccination against COVID-19. | according to age group. | 12 months | 
| Evaluate the effectiveness of the vaccination against COVID-19. | according to the presence of comorbidities and medication use. | 12 months | 
| Evaluate the effectiveness of the vaccination against COVID-19. | according to Region/State. | 12 months | 
| Evaluate the effectiveness of the vaccination against COVID-19. | according to vaccination coverage. | 12 months | 
| Evaluate the effectiveness of the vaccination against COVID-19. | according to circulating viral variants. | 12 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assess the humoral and cellular immune response | in vaccinated or unvaccinated cases compared to vaccinated or unvaccinated controls. | 15 months | 
| Analyze individual factors | including those related to the adaptive immune response (HLA molecules) and genetic aspects, in severe cases/deaths associated with vaccine failures. | 15 months |