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

Abstract

Introduction: 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.

Methods: 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).

Results: 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.

Conclusions: 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.

Keywords: COVID-19; SARS-CoV-2; booster shot; cohort study; infection; lifestyle habit; vaccine.

Figure 1.

Participants of the TMM BirThree Cohort Study cohort and analyzed subjects The TMM BirThree Cohort Study recruited 73,529 participants from July 2013 to March 2017, of whom 39,667 were adults. Among the adult participants, 26,212 who were residing in Sendai City were linked to the information on the COVID-19 vaccination and SARS-CoV-2 infection. Finally, 11,016 adult participants who completed the questionnaire were analyzed.

Figure 2.

Number of SARS-CoV-2 cases and definition of the two periods The first period was from April 2021 to May 2022, which was the beginning phase of the COVID-19 vaccination program targeting the entire adult population. The second period was from June 2022 onward, which was initiated with a fourth shot targeting the elderly, those who have underlying health conditions, and healthcare professionals.

Figure 3.

Time-dependent variables of the final date of vaccination and SARS-CoV-2 infection (first and second periods: 2021.4-2023.5) Vertical axis: Rate of SARS-CoV-2 infection. Horizontal axis: Analysis time (months). Cox proportional-hazards model analysis was conducted while adjusting for age (categorical), underlying health conditions, exercise habits, smoking and drinking habits (categorical), sleep status, body mass index (categorical), and breakfast consumption.

Figure 4.

Visualization of interaction between lifestyle habits and the number of vaccinations against SARS-CoV-2 infection Logistic regression analyses were conducted stratifying the lifestyle variables. The figure in the upper portion illustrates the first period, whereas that in the lower portion shows the second period. Blue indicates lower risk of SARS-CoV-2 infection, whereas red indicates higher risk of infection.