FOUR-YEAR EFFECTIVENESS OF COVID-19 VACCINES AGAINST SEVERE DISEASE AND ASYMPTOMATIC INFECTION: THE COVIDVAC@SPAIN STUDY

Study type

• Study type:
  Non-interventional study
• Scope of the study:
  Effectiveness study (incl. comparative)

Non-interventional study

• Non-interventional study design:
  Other
• Non-interventional study design, other:
  Retrospective observational epidemiological study

Study drug and medical condition

• Medical condition to be studied:
  COVID-19 immunisation

Population studied

• Age groups:
  • Adults (18 to < 46 years)
  • Adults (46 to < 65 years)
  • Adults (65 to < 75 years)
  • Adults (75 to < 85 years)
  • Adults (85 years and over)
• Estimated number of subjects:
  33600

Study design details

• Main study objective:
  Estimate: 1) vaccine effectiveness (VE) of approved COVID vaccines in preventing asymptomatic infection, 2) the viral replication difference in vaccinated vs non-vaccinated subjects, 3) the VE of approved COVID vaccines in preventing severe outcomes in persons who require hospitalization, 4) if the VE from objective #3 varies according to SARS-CoV-2 variants or strains carrying specific mutation
• Outcomes:
  Substudy A: SARS-CoV-2 PCR positive/negative results Substudy B: • Maximum level of oxygen support required • ICU admission (and duration) • Mechanical ventilation (and duration) • Pulmonary embolism • Death or discharge hospitalization • Total duration of hospital stay, Interaction between vaccination. Variant-specific VE
• Data analysis plan:
  For main objective #1, multivariate logistic regression will be used. For main objective #2 a sub-analysis of positive cases will be carried out and mean Ct values will be compared between vaccinated and non-vaccinated groups using generalized linear models. For main objectives #3 and #4, longitudinal data will be analysed using either multivariate Poisson models or survival analysis and Cox regression. For secondary objectives #1, #2 and #3, interaction between vaccination and independent variables will be tested, and stratified estimations in groups defined by vaccination schedule, age, sex, previous SARS-CoV-2 infection and comorbidities will be performed.For secondary objective #4 all project data will be pooled and an interaction between study period (selection-round) and vaccination status will be tested to analyse statistically significant variation in VE. Stata v15.0.