The Corona Immunitas Digital Follow-Up eCohort to Monitor Impacts of the SARS-CoV-2 Pandemic in Switzerland: Study Protocol and First Results.

Alexandre Speierer,Silvia Stringhini,Fabian Vollrath,Éric Salberg,Elsa Lorthe,Nathalie Schwab,Rebecca Amati,Laurie Corna,Chantal Luedi,Gisela Michel,Sara Levati,Giovanni Franscella,Anja Frei,Ismaël Tall,Medea Imboden,Thomas Vermes,Viktor Von Wyl,Christian Kahlert,Caroline Veys-Takeuchi,Marco Geigges,Stéphane Cullati,Semira Gonseth Nusslé,Daniela Anker,Marco Kaufmann,Francesco Pennacchio,Milo A Puhan,Claire Zuppinger,Nicolas Rodondi,Hélène Baysson,Dirk Keidel,Valérie D’Acremont,Erika Harju,Erin West ,Nicole Probst‐Hensch ,Arnaud Chioléro ,Alexandra Schmid ,Patricia Chocano-Bedoya

doi:10.3389/ijph.2022.1604506

Abstract

Objectives: To describe the rationale, organization, and procedures of the Corona Immunitas Digital Follow-Up (CI-DFU) eCohort and to characterize participants at baseline. Methods: Participants of Corona Immunitas, a population-based nationwide SARS-CoV-2 seroprevalence study in Switzerland, were invited to join the CI-DFU eCohort in 11 study centres. Weekly online questonnaires cover health status changes, prevention measures adherence, and social impacts. Monthly questionnaires cover additional prevention adherence, contact tracing apps use, vaccination and vaccine hesitancy, and socio-economic changes. Results: We report data from the 5 centres that enrolled in the CI-DFU between June and October 2020 (covering Basel City/Land, Fribourg, Neuchâtel, Ticino, Zurich). As of February 2021, 4636 participants were enrolled and 85,693 weekly and 27,817 monthly questionnaires were collected. Design-based oversampling led to overrepresentation of individuals aged 65+ years. People with higher education and income were more likely to enroll and be retained. Conclusion: Broad enrolment and robust retention of participants enables scientifically sound monitoring of pandemic impacts, prevention, and vaccination progress. The CI-DFU eCohort demonstrates proof-of-principle for large-scale, federated eCohort study designs based on jointly agreed principles and transparent governance.

Highlights

Mitigating the consequences of the ongoing Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic requires sound evidence on ever-changing medical, scientific, economic and social issues
In the Results section we present the characteristics of participants enrolled during CI study phase 2 compared to the general population, evaluating representativeness of our sample
We present key baseline characteristics of participants from the five Corona Immunitas sites that initiated digital follow-up assessments during CI study phase 2 in June 2020 (Basel, Fribourg, Neuchâtel, Ticino, Zurich)

Summary

Introduction

Mitigating the consequences of the ongoing Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic requires sound evidence on ever-changing medical, scientific, economic and social issues. Recent examples are the individuallevel and population-based impacts of vaccinations [1, 2] or clinical and social implications of long COVID [3, 4]. Anticipating the need for a flexible study base, a consortium was founded in Switzerland in spring 2020. The primary aim of Corona Immunitas is to assess the nationwide, populationbased seroprevalence (as measured by antibodies against nucleoid and spike proteins) of SARS-CoV-2 during different pandemic phases among randomly selected individuals from the general population, as well as in selected subgroups such as highly exposed healthcare workers or essential workers, such as bus drivers. The first three study phases saw an expansion of Corona Immunitas into further regions in Switzerland

Objectives

Methods

Results

Conclusion