@Article{info:doi/10.2196/47070,
author="Lang, Anna-Lena
and Hohmuth, Nils
and Vi{\v{s}}kovi{\'{c}}, Vuka{\v{s}}in
and Konigorski, Stefan
and Scholz, Stefan
and Balzer, Felix
and Remschmidt, Cornelius
and Leistner, Rasmus",
title="COVID-19 Vaccine Effectiveness and Digital Pandemic Surveillance in Germany (eCOV Study): Web Application--Based Prospective Observational Cohort Study",
journal="J Med Internet Res",
year="2024",
month="Jun",
day="4",
volume="26",
pages="e47070",
keywords="COVID-19; SARS-CoV-2; COVID-19 vaccines; BNT162b2; vaccine effectiveness; participatory disease surveillance; web application; digital public health; vaccination; Germany; effectiveness; data collection; disease surveillance; tool",
abstract="Background: The COVID-19 pandemic posed significant challenges to global health systems. Efficient public health responses required a rapid and secure collection of health data to improve the understanding of SARS-CoV-2 and examine the vaccine effectiveness (VE) and drug safety of the novel COVID-19 vaccines. Objective: This study (COVID-19 study on vaccinated and unvaccinated subjects over 16 years; eCOV study) aims to (1) evaluate the real-world effectiveness of COVID-19 vaccines through a digital participatory surveillance tool and (2) assess the potential of self-reported data for monitoring key parameters of the COVID-19 pandemic in Germany. Methods: Using a digital study web application, we collected self-reported data between May 1, 2021, and August 1, 2022, to assess VE, test positivity rates, COVID-19 incidence rates, and adverse events after COVID-19 vaccination. Our primary outcome measure was the VE of SARS-CoV-2 vaccines against laboratory-confirmed SARS-CoV-2 infection. The secondary outcome measures included VE against hospitalization and across different SARS-CoV-2 variants, adverse events after vaccination, and symptoms during infection. Logistic regression models adjusted for confounders were used to estimate VE 4 to 48 weeks after the primary vaccination series and after third-dose vaccination. Unvaccinated participants were compared with age- and gender-matched participants who had received 2 doses of BNT162b2 (Pfizer-BioNTech) and those who had received 3 doses of BNT162b2 and were not infected before the last vaccination. To assess the potential of self-reported digital data, the data were compared with official data from public health authorities. Results: We enrolled 10,077 participants (aged ≥16 y) who contributed 44,786 tests and 5530 symptoms. In this young, primarily female, and digital-literate cohort, VE against infections of any severity waned from 91.2{\%} (95{\%} CI 70.4{\%}-97.4{\%}) at week 4 to 37.2{\%} (95{\%} CI 23.5{\%}-48.5{\%}) at week 48 after the second dose of BNT162b2. A third dose of BNT162b2 increased VE to 67.6{\%} (95{\%} CI 50.3{\%}-78.8{\%}) after 4 weeks. The low number of reported hospitalizations limited our ability to calculate VE against hospitalization. Adverse events after vaccination were consistent with previously published research. Seven-day incidences and test positivity rates reflected the course of the pandemic in Germany when compared with official numbers from the national infectious disease surveillance system. Conclusions: Our data indicate that COVID-19 vaccinations are safe and effective, and third-dose vaccinations partially restore protection against SARS-CoV-2 infection. The study showcased the successful use of a digital study web application for COVID-19 surveillance and continuous monitoring of VE in Germany, highlighting its potential to accelerate public health decision-making. Addressing biases in digital data collection is vital to ensure the accuracy and reliability of digital solutions as public health tools. ",
issn="1438-8871",
doi="10.2196/47070",
url="https://www.jmir.org/2024/1/e47070",
url="https://doi.org/10.2196/47070",
url="http://www.ncbi.nlm.nih.gov/pubmed/38833299"
}