Association Between Cigarette Smoking and SARS-CoV-2 Infection: Insights from Multivariable Regression and Mendelian Randomization in the Norwegian Mother, Father and Child Cohort Study

By
Ida Henriette Caspersen
Álvaro Hernáez
Sebastián Peña
Ahmed Nabil Shaaban
Maria Christine Magnus
Sakari Karvonen
Maria Rosaria Galanti
Per Magnus
February 4, 2026
0 min

Bmc Infectious Diseases

Overview

This study investigates the association between smoking traits and the risk of SARS-CoV-2 infection using multivariable regression and Mendelian randomization analyses. It highlights conflicting evidence regarding smoking's impact on COVID-19 outcomes and emphasizes the need for understanding these associations.

Background

The relationship between smoking and COVID-19 outcomes is critical, as smokers have been shown to have increased risks of severe disease and long-term complications from SARS-CoV-2 infection. Observational studies have reported lower rates of confirmed infections among smokers, raising questions about the causal nature of these associations. Understanding these dynamics is essential for effective public health communication and intervention strategies.

Data Highlights

No specific numerical data or trial results were provided in the source material.

Key Findings

Mendelian randomization studies suggest a positive association between genetically predicted smoking traits and confirmed SARS-CoV-2 infection.
Standard observational studies indicate that current smokers have a lower risk of testing positive for SARS-CoV-2 compared to non-smokers.
Confounding factors and biases may explain discrepancies between observational and MR study results.
Risk-taking behavior may violate the pleiotropy assumption in MR analyses, impacting the validity of findings.
Understanding the health effects of smoking is crucial for effective risk communication, especially during pandemics.

Clinical Implications

Healthcare professionals should be aware of the complexities surrounding smoking and COVID-19 risk. Smoking should not be considered protective against SARS-CoV-2 infection, and clinicians should continue to emphasize smoking cessation and risk stratification in patient management.

Conclusion

The study underscores the importance of reconciling conflicting evidence regarding smoking and COVID-19 outcomes to inform public health strategies. Continued research is necessary to clarify these associations and their implications for patient care.