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Int J Epidemiol
. 2026 Feb 18;55(2):dyag031.
doi: 10.1093/ije/dyag031.
The effect of SARS-CoV-2 testing on healthcare-seeking behaviour at primary care level
Cheyenne C E van Hagen 1 , Eric R A Vos 1 , Charlotte Lanièce Delaunay 2 , Hester E de Melker 1 , Esther Kissling 2 , Mirjam J Knol 1
Affiliations
Background: Diagnostic self-testing for SARS-CoV-2 may lead to selection bias in test-negative case-control designs (TND) for COVID-19 vaccine effectiveness (VE) at the primary care level. We investigated whether SARS-CoV-2 self-testing among those with acute respiratory infection (ARI) after the acute pandemic phase was associated with primary care healthcare seeking in the general Dutch population.
Methods: We pooled questionnaire data from three study rounds (June 2022, November 2022, and April 2023) of the nationwide PIENTER Corona cohort study. Among 3152 participants aged ≥18 years, we selected the first self-reported ARI episode with cough, sore throat, dyspnoea, and/or coryza since March 2022. We performed log-binomial regression analyses adjusted for age, sex, education, and comorbidities to assess the associations between COVID-19 vaccination, SARS-CoV-2 self-testing, and general practitioner (GP) consultation, and between GP consultation and the prior self-test result.
Results: Vaccinated (vs. unvaccinated) participants with an ARI episode more often self-tested [adjusted risk ratio (RR) 1.13, 95% confidence interval (CI) 1.04-1.27]. Vaccination (RR 0.78, 95% CI 0.48-1.44) and the self-test result overall (RR 0.86, 95% CI 0.69-1.08) were both not associated with GP consultation. However, with point estimates in opposite directions, vaccinated individuals seemed less likely (RR 0.86, 95% CI 0.68-1.08) and unvaccinated seemed more likely (RR 1.57, 95% CI 0.36-6.28) to consult a GP after a positive self-test.
Conclusion: Findings from this Dutch-population-based cohort suggest that GP consultations between March 2022 and May 2023 may have differed by self-test result and vaccination status, indicating that selection bias in the TND COVID-19 VE estimates from testing before GP consultation could be a valid concern. More research in various settings is needed.
Keywords: SARS-CoV-2; healthcare-seeking behaviour; prospective cohort study; self-test; test-negative study design; vaccine effectiveness.
. 2026 Feb 18;55(2):dyag031.
doi: 10.1093/ije/dyag031.
The effect of SARS-CoV-2 testing on healthcare-seeking behaviour at primary care level
Cheyenne C E van Hagen 1 , Eric R A Vos 1 , Charlotte Lanièce Delaunay 2 , Hester E de Melker 1 , Esther Kissling 2 , Mirjam J Knol 1
Affiliations
- PMID: 41808425
- DOI: 10.1093/ije/dyag031
Background: Diagnostic self-testing for SARS-CoV-2 may lead to selection bias in test-negative case-control designs (TND) for COVID-19 vaccine effectiveness (VE) at the primary care level. We investigated whether SARS-CoV-2 self-testing among those with acute respiratory infection (ARI) after the acute pandemic phase was associated with primary care healthcare seeking in the general Dutch population.
Methods: We pooled questionnaire data from three study rounds (June 2022, November 2022, and April 2023) of the nationwide PIENTER Corona cohort study. Among 3152 participants aged ≥18 years, we selected the first self-reported ARI episode with cough, sore throat, dyspnoea, and/or coryza since March 2022. We performed log-binomial regression analyses adjusted for age, sex, education, and comorbidities to assess the associations between COVID-19 vaccination, SARS-CoV-2 self-testing, and general practitioner (GP) consultation, and between GP consultation and the prior self-test result.
Results: Vaccinated (vs. unvaccinated) participants with an ARI episode more often self-tested [adjusted risk ratio (RR) 1.13, 95% confidence interval (CI) 1.04-1.27]. Vaccination (RR 0.78, 95% CI 0.48-1.44) and the self-test result overall (RR 0.86, 95% CI 0.69-1.08) were both not associated with GP consultation. However, with point estimates in opposite directions, vaccinated individuals seemed less likely (RR 0.86, 95% CI 0.68-1.08) and unvaccinated seemed more likely (RR 1.57, 95% CI 0.36-6.28) to consult a GP after a positive self-test.
Conclusion: Findings from this Dutch-population-based cohort suggest that GP consultations between March 2022 and May 2023 may have differed by self-test result and vaccination status, indicating that selection bias in the TND COVID-19 VE estimates from testing before GP consultation could be a valid concern. More research in various settings is needed.
Keywords: SARS-CoV-2; healthcare-seeking behaviour; prospective cohort study; self-test; test-negative study design; vaccine effectiveness.