Research question and objectives:
Overall research question: What is the relative effectiveness of receiving BIMERVAX® vaccine on COVID-19–related outcomes compared with receipt of another authorised
COVID-19 vaccine for the same indication?
Objectives:
?? The primary objective is to estimate the effect of BIMERVAX® on the following COVID-19–related outcome compared with other COVID-19 vaccines authorised for the same indication:
– Primary outcome: COVID-19–requiring a hospitalisation or emergency department (ED) visit
?? The secondary objective is to estimate the effect of BIMERVAX® on the following COVID-19–related outcome compared with other COVID-19 vaccines authorised for the same indication:
– Secondary outcome: COVID-19 diagnosis in any setting
Study design: A cohort design will be used to estimate the effectiveness of BIMERVAX® on COVID-19–related outcomes compared with other COVID-19 vaccines.
Population: The eligible population will be all individuals who have received a dose of BIMERVAX® or a comparator COVID-19 vaccine and are actively enroled in one of the selected European health data sources for at least 12 months before receipt of the vaccination.
The study period will begin from the date of first availability of the BIMERVAX® original vaccine in each participating data source and will end 36 months after the start of data collection. The start of data collection will be anchored on the threshold of a total of 4,000 BIMERVAX® doses administered across the participating data sources.
Variables:
?? Exposures will be based on recorded prescription, dispensing, or administration of COVID-19 vaccines during the study period.
The outcomes will be based on recorded diagnoses of COVID-19, which will be identified as COVID-19 requiring a hospitalisation or ED visit or COVID-19 diagnosis in any medical care setting.
?? Key confounders will include demographics, COVID-19 history, vaccinations, personal lifestyle characteristics, comorbidities, comedications, immunocompromising conditions, and others.
?? Subgroups will be defined by baseline variables such as comorbidities, immunocompromised status, vaccinations, and others.
Data sources: The planned data sources for this study, pending vaccine rollout confirmation, are EpiChron (Spain), Information System for Research in Primary Care (SIDIAP) (Spain), and Valencia Health System Integrated Database (VID) (Spain). Rollout in other European countries will be monitored to evaluate other potential data sources
Study size: The study size for the effectiveness study will be determined by the uptake of BIMERVAX® in the participating data sources.
Data analysis: The cohort study will estimate the risk of COVID-19–related outcomes among individuals receiving BIMERVAX® compared with that among individuals receiving a contemporary COVID-19 vaccine. The data analysis will be characterised by the following Baseline will be defined as the date on which eligible individuals receive the vaccine (BIMERVAX® or a comparator vaccine). Follow-up starts and eligibility criteria are applied at baseline.
Eligible vaccinated individuals will be followed from baseline until the occurrence of a COVID-19–related outcome, death, disenrolment from the data source, or end of the study period, whichever occurs first.
?? The study will estimate the effect of receiving 1 dose of BIMERVAX® versus the effect of receiving 1 dose of other COVID-19 vaccines. Standard epidemiological methods will be used to achieve baseline exchangeability conditional on the measured
confounders.
?? Outcomes will be treated as time-to-event variables and will be analysed accordingly. Effect estimates will be provided in both relative (e.g., risk ratio) and absolute (e.g., risk differences) scales. Relative vaccine effectiveness will be estimated as
1 minus the risk ratio.
