Related Experiment Video
Updated: Jan 13, 2026
03:53
Author Spotlight: Advancements in Multiplex Detection of Respiratory Viruses
Published on: November 10, 2023
1.8K
Precautionary Health Behaviours as Potential Confounders in COVID-19 Vaccine Effectiveness Studies
Chloé Wyndham-Thomas1, Leonie de Munter2, Kok Yew Ngew1
1P95 Clinical and Epidemiology Services, Diestsevest 125, 3000 Leuven, Belgium.
Vaccines
|October 28, 2025
Summary
Precautionary health behaviors (PHBs) confounded COVID-19 vaccine effectiveness (VE) estimates during the first booster season, increasing VE by 6-9%. Confounding was not observed in the second season, indicating context-dependent effects.
Area of Science:
- Epidemiology
- Public Health
- Infectious Disease Control
Background:
- Precautionary health behaviors (PHBs) are crucial non-pharmaceutical interventions for reducing SARS-CoV-2 transmission.
- Investigating PHBs' confounding effect on COVID-19 vaccine effectiveness (VE) is vital for accurate public health guidance.
Purpose of the Study:
- To assess the impact of PHBs on COVID-19 VE estimates in a European test-negative case-control study.
- To determine if PHBs act as a confounder in VE calculations during different COVID-19 vaccination periods.
Main Methods:
- A European multicentre test-negative case-control study (id.DRIVE) enrolled adults with severe acute respiratory infection.
- Surveys captured PHB indicators in the 3 months prior to admission; Fisher's exact test analyzed associations.
- VE estimates were calculated with and without adjustment for PHBs.
Main Results:
- PHBs varied between the first (2021-2022) and second (2022-2023) COVID-19 booster seasons.
- During the first booster season, PHBs confounded VE estimates, increasing them by 6-9 percentage points.
- No significant confounding by PHBs was detected during the second booster season.
Conclusions:
- PHBs can be a significant confounder in COVID-19 VE studies.
- The degree of confounding by PHBs is context-dependent and varies by study population and epidemiological situation.
- Further research is needed to establish guidelines for incorporating PHBs into VE models.
Related Concept Videos
01:27Confounding in Epidemiological Studies
570
Confounding in statistical epidemiology represents a pivotal challenge, referring to the distortion in the perceived relationship between an exposure and an outcome due to the presence of a third variable, known as a confounder. This variable is associated with both the exposure and the outcome but is not a direct link in their causal chain. Its presence can lead to erroneous interpretations of the exposure's effect, either exaggerating or underestimating the true association. This...
570
01:29Bias in Epidemiological Studies
1.3K
Biases can arise at various stages of research, from study design and data collection to analysis and interpretation. Recognizing and addressing these biases is essential to ensure the validity and reliability of epidemiological findings.Broadly speaking, biases in epidemiology fall into three main categories: selection bias, information bias, and confounding. A more detailed description of possible biases is:
1.3K
01:26Factors Affecting the Risk of Infection
13.2K
The hosts' susceptibility to infection depends on several factors. The integrity of the skin and mucous membranes helps protect the body against microbial attacks. When the skin is altered, the chance of infection, limb loss, and even death increases.
The integrity and count of the white blood cells help the body resist pathogens and fight infection. When impaired, it reduces the body's resistance to pathogens. The acidic pH levels of the gastrointestinal, genitourinary tracts, and skin...
The integrity and count of the white blood cells help the body resist pathogens and fight infection. When impaired, it reduces the body's resistance to pathogens. The acidic pH levels of the gastrointestinal, genitourinary tracts, and skin...
13.2K
01:23Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches
397
Biopharmaceutical studies constitute a vital field aiming to enhance drug delivery methods and refine therapeutic approaches, drawing upon diverse interdisciplinary knowledge. In research methodologies, the choice between controlled and non-controlled studies significantly influences the study's reliability and accuracy.
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast,...
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast,...
397
01:12What is an Experiment?
17.3K
An experiment is a planned activity carried out under controlled conditions. The purpose of an experiment is to investigate the relationship between two variables. When one variable causes change in another, we call the first variable the explanatory or independent variable. The affected variable is called the response or dependent variable. In a randomized experiment, the researcher manipulates values of the explanatory variable and measures the resulting changes in the response variable. The...
17.3K
01:25Strategies for Assessing and Addressing Confounding
356
Confounding is a critical issue in epidemiological studies, often leading to misleading conclusions about associations between exposures and outcomes. It occurs when the relationship between the exposure and the outcome is mixed with the effects of other factors that influence the outcome. Given that, addressing confounding is of high importance for drawing accurate inferences in research.
Confounding can be addressed at both the design phase of a study and through analytical methods after data...
Confounding can be addressed at both the design phase of a study and through analytical methods after data...
356