Poor stress resilience in adolescence predicts higher risk of severe COVID-19 and other respiratory infections: A prospective cohort study of 1.4 million Swedish men

Objectives

To investigate the associations between stress resilience in late adolescence and later risk of severe COVID-19 and other lower respiratory infections. A secondary aim was to examine potential confounding between low cardiorespiratory fitness (CRF) and stress resilience in relation to respiratory infection.

Methods

We conducted a registry-based cohort study of 1.4 million Swedish men, undergoing military conscription between 1968 and 2005. All were assessed by a psychologist for stress resilience, receiving a score between 1 and 9. The outcomes were hospitalization or death due to COVID-19 from March 2020 to September 2021 and hospitalization due to bacterial or viral pneumonia from conscription until January 2020. A secondary aim was to examine potential confounding between low cardiorespiratory fitness (CRF) and stress resilience in relation to respiratory infection.

Results

Poor stress resilience in late adolescence is associated with later risk of severe lower respiratory infections. Using a high resilience score as the reference, the hazard ratio (95 % CI) for death due to COVID-19 for the lowest scores was 1.49 (1.01–2.18) adjusted for CRF and other confounders. The corresponding adjusted hazard ratios for hospitalization due to bacterial pneumonia were 2.28 (2.03–2.57) and for viral pneumonia 1.92 (1.33–2.79). No significant interaction was seen between stress resilience and CRF in the analysis.

Conclusions

Poor stress resilience is a prospective factor for severe COVID-19 as well as for bacterial and viral respiratory pneumonia endpoints, independent of CRF. These findings imply an effect of late adolescent stress resilience on the immune system later in life.