The aim of this study was to analyse associations between crowded housing and children’s indoor living environment, respiratory and allergic disorders and general health.

A cross-sectional study.

Sweden, using data from the Swedish National Environmental Health Survey 2019.

The study sample included 48 512 children (aged 6–10 months, 4 years and 12 years). We also investigated associations in vulnerable subgroups, such as children with asthma and those living under unfavourable socioeconomic conditions.

Primary outcomes in the living environment were at least one sign of mould, poor indoor air quality, unpleasant odours, too warm indoors in summer and too cold indoors in winter. Primary outcomes for children’s health were asthma, airway problems, breathing difficulties, rhinitis symptoms, mould and mites allergy, pollen allergy, furred pet allergy and good general health.

About one in five children lived in an overcrowded home. Factors from the indoor living environment such as perceived poor indoor air quality and mould were significantly associated with crowded housing. Moreover, children who lived in overcrowded conditions were less likely to report good general health than children in non-crowded households (OR 0.64, 95% CI 0.54 to 0.76). This association was even stronger in children with asthma (OR 0.51, 95% CI 0.34 to 0.77). Few significant associations were, however, observed with the respiratory and allergic health outcomes.

Crowded housing is associated both with a poor indoor environment and with poorer general health in children. Children with asthma may experience even poorer general health.

Current guideline-recommended antibiotic treatment durations for ventilator-associated pneumonia (VAP) are largely standardised, with limited consideration of individual patient characteristics, pathogens or clinical context. This one-size-fits-all approach risks both overtreatment—promoting antimicrobial resistance and adverse drug events—as well as undertreatment, increasing the likelihood of pneumonia recurrence and sepsis-related complications. There is a critical need for VAP-specific biomarkers to enable individualised treatment strategies. The Ventilator-associated pneumonia Biomarker Evaluation (VIBE) study aims to identify a dynamic alveolar biomarker signature associated with treatment response, with the goal of informing personalised antibiotic duration in future clinical trials.

VIBE is a prospective, observational, case-cohort study of 125 adult patients with VAP in Michigan Medicine University Hospital intensive care units. Study subjects will undergo non-bronchoscopic bronchoalveolar lavage on the day of VAP diagnosis (Day 1) and then on Days 3 and 5. Alveolar biomarkers (quantitative respiratory culture bioburden, alveolar neutrophil percentage and pathogen genomic load assessed via BioFire FilmArray polymerase chain reaction) will be assessed. An expert panel of intensivists, blinded to biomarker data, will adjudicate each patient’s Day 10 outcome as VAP clinical cure (control) or treatment failure (case). Absolute biomarker levels and mean-fold changes in biomarker levels will be compared between groups. Data will be used to derive a composite temporal alveolar biomarker signature predictive of VAP treatment failure.

Ethical approval was obtained from the University of Michigan Institutional Review Board (IRB #HUM00251780). Informed consent will be obtained from all study participants or their legally authorised representatives. Findings will be disseminated through peer-reviewed publications, conferences and feedback into clinical guidelines committees.