# How Healthy Lifestyle Habits Have Interacted with SARS-CoV-2 Infection and the Effectiveness of COVID-19 Vaccinations: Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study

## TL;DR

This study explores how lifestyle habits and the number of COVID-19 vaccinations affect the risk of SARS-CoV-2 infection.

## Contribution

The study reveals that more vaccinations are linked to lower infection risk, with lifestyle factors having limited additional impact.

## Key findings

- Higher vaccination counts significantly reduced SARS-CoV-2 infection risk in logistic regression analysis.
- Lifestyle factors like sleep satisfaction had minor effects on risk reduction during the first vaccination period.
- The protective effect of vaccinations remained strong regardless of lifestyle habits.

## Abstract

To examine the interaction between lifestyle habits and the COVID-19 vaccinations for preventing SARS-CoV-2 infection, we analyzed 11,016 adult participants registered in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study.

Lifestyle variables, including regular exercise, smoking and drinking habits, sleep status, body mass index, and daily breakfast consumption, were assessed from 2014 to 2019 using baseline questionnaires. Information on SARS-CoV-2 infection and the COVID-19 vaccination were also collected from March 2020 to May 2023. The study period was divided into two in the postvaccination phase: the first period (the beginning of the vaccination program) and the second period (the fourth shot onward).

In the Cox proportional-hazards model analysis, the five-time vaccinations group showed a significantly lower risk of SARS-CoV-2 infection adjusted age, sex, underlying health condition, and lifestyle variables (hazard ratio [HR] 0.81, 95% confidence interval [CI] 0.76-0.86). Logistic regression analysis revealed that a higher number of vaccinations was significantly associated with a low risk of SARS-CoV-2 infection regardless of lifestyle habits (three times in the first period: odds ratio [OR] 0.19, 95% CI 0.15-0.24; five times in the second period: OR 0.07, 95% CI 0.05-0.11 vs. none). Regarding lifestyle habits, the risk reduction in those who had sleep satisfaction (OR 0.12, 95% CI 0.08-0.18) was slightly larger than in those who had sleep dissatisfaction (OR 0.23, 95% CI 0.17-0.32) in the group with the highest number of vaccinations in the first period; however, this interaction was hardly confirmed in the second period when the number of infected cases significantly increased.

Our findings indicated that a higher number of COVID-19 vaccinations was associated with reduced risk of SARS-CoV-2 infection; otherwise, we may need to understand the advantages and limitations of a healthy lifestyle for preventing infection depending on the situation with vaccinations and infection spreading.