Year of publication: The year in which the original article from which the data was extracted was published

Reporting year (Blood Donors only): The year for which the data extracted was reported to the publishing authority i.e. Council of Europe

Country: Country hosting the population for which the study/report provides seroprevalence estimates

Geographical coverage: Coverage of the sample population by the study design, in geographic terms

Last year of recruitment: Year during which the recruitment of participants was concluded

Study population: Description of sample population

Sampling method: Description or characteristics of sampling method

Total sampled: Total number of individuals invited to be a participant (denominator)

Response rate: Proportion of invited who accepted to be tested. Calculated as number tested/total sampled unless otherwise reported in the study.

Country/Region of origin (Migrants only): Refers to country of birth/ethnicity or country of birth/ethnicity of parents

Generation (Migrants only): 
First: People who are foreign-born
Second: People considered migrants based on their ethnicity (e.g. self-reported or where one/both parents are foreign-born), but who themselves are born in the country of residence

Age range: Categorised as minimum and maximum, in years. Not a filterable variable.

Age group: 
Children: <18 years
Adults: ≥18 years
All: Both adults and children i.e. <18 years and ≥18

Note that some studies may classify >15 years as adults

Specimen: Biological material collected from the participant/cadaver for the diagnostic test

Diagnostic test: Type of laboratory test used for the detection of the biomarker

Biomarker: Specific biomarker detected by the diagnostic test

Number tested: Number of individuals who were tested (numerator)

Number positive: Number of individuals found to be positive for the biomarker

Point estimate of prevalence: Proportion of number tested who were found positive, calculated as number positive/number tested as a percentage

95% CI of estimate: 95% confidence interval of the prevalence estimate calculated using Fischer method or any other method as specified in the study. Includes lower and upper CI of the estimate.

Risk of bias: An ad hoc risk of bias framework as developed by the original ECDC review team (reference), that assessed different domains across populations. Points were given for representativeness or lower risk of bias in each domain, and the total score obtained by adding up scores across domains. Higher scores indicate lower risk of bias.

General population: Domains assessed: age, gender, sampling method & response rate and population coverage

Pregnant women: Domains assessed: sampling method and population coverage

MSM: Domain assessed: Sampling venue coverage

Prisoners: Domains assessed: age, gender, proportion of PWID, sampling method and population coverage

Source: The study or report from which the data was obtained.