PT  - JOURNAL ARTICLE
AU  - Vos, Eric R A
AU  - den Hartog, Gerco
AU  - Schepp, Rutger M
AU  - Kaaijk, Patricia
AU  - van Vliet, Jeffrey
AU  - Helm, Kina
AU  - Smits, Gaby
AU  - Wijmenga-Monsuur, Alienke
AU  - Verberk, Janneke D M
AU  - van Boven, Michiel
AU  - van Binnendijk, Rob S
AU  - de Melker, Hester E
AU  - Mollema, Liesbeth
AU  - van der Klis, Fiona R M
TI  - Nationwide seroprevalence of SARS-CoV-2 and identification of risk factors in the general population of the Netherlands during the first epidemic wave
AID  - 10.1136/jech-2020-215678
DP  - 2021 Jun 01
TA  - Journal of Epidemiology and Community Health
PG  - 489--495
VI  - 75
IP  - 6
4099  - http://jech.bmj.com/content/75/6/489.short
4100  - http://jech.bmj.com/content/75/6/489.full
SO  - J Epidemiol Community Health2021 Jun 01; 75
AB  - Background We aimed to detect SARS-CoV-2 serum antibodies in the general population of the Netherlands and identify risk factors for seropositivity amidst the first COVID-19 epidemic wave.Methods Participants (n=3207, aged 2–90 years), enrolled from a previously established nationwide serosurveillance study, provided a self-collected fingerstick blood sample and completed a questionnaire (median inclusion date 3 April 2020). IgG antibodies targeted against the spike S1-protein of SARS-CoV-2 were quantified using a validated multiplex-immunoassay. Seroprevalence was estimated controlling for survey design, individual pre-pandemic concentration, and test performance. Random-effects logistic regression identified risk factors for seropositivity.Results Overall seroprevalence in the Netherlands was 2.8% (95% CI 2.1 to 3.7), with no differences between sexes or ethnic background, and regionally ranging between 1.3 and 4.0%. Estimates were highest among 18–39 year-olds (4.9%), and lowest in children 2–17 years (1.7%). Multivariable analysis revealed that persons taking immunosuppressants and those from the Orthodox-Reformed Protestant community had over four times higher odds of being seropositive compared to others. Anosmia/ageusia was the most discriminative symptom between seropositive (53%) and seronegative persons (4%, p<0.0001). Antibody concentrations in seropositive persons were significantly higher in those with fever or dyspnoea in contrast to those without (p=0.01 and p=0.04, respectively).Conclusions In the midst of the first epidemic wave, 2.8% of the Dutch population was estimated to be infected with SARS-CoV-2, that is, 30 times higher than reported. This study identified independent groups with increased odds for seropositivity that may require specific surveillance measures to guide future protective interventions internationally, including vaccination once available.