Table 2.

Covariates associated with the incidence and severity of the respiratory syncytial virus.

Covariate	Categories
Age	As whole years 5-year increments (broader 10-year age bands may be considered)
Sex	Male or female
Ethnicity	White, Asian, Black, other, or mixed
Region	Divided into areas served by an integrated care system
Urban or rural designation	Urban or rural
Household composition	Divided into categories 1, 2, 3, 4-5, 6-10, 11, or more
Socioeconomic status will be measured using the index of multiple deprivation [32]	Quintiles from 1 (most deprived), 2, 3, 4, and 5 (least deprived)
BMI	Obese or not obese (BMI ≥ or <30), Also stratified as <18.5, 18.5-24.9, 25.0-29.9, 30.0-39.9, 40.0, or more)
Smoking status	Current smoker, previous smoker, or nonsmoker
Cambridge Multi-Morbidity Score	Quartiles No comorbidities, 1, 2, 3, 4, or more comorbidities
Comorbidities known to relate to increased risk of severe respiratory illness, or suboptimal vaccine response, or vaccine contraindication	Chronic respiratory disease Chronic obstructive pulmonary disease Chronic heart failure Chronic heart disease and vascular disease Chronic kidney disease Chronic liver disease Chronic neurological disease Diabetes mellitus Severe mental illness Morbid obesity Asplenia, or dysfunction of the spleen, immunosuppression due to disease, or treatment
Vaccination status within the season	Influenza vaccination COVID-19 vaccination Pneumococcal vaccination