Multi-site placebo-controlled randomised clinical trial to assess protection following oral immunisation with inactivated non-typeable Haemophilus influenzae in chronic obstructive pulmonary disease.

BACKGROUND: Previous studies identified factors that modify response to an oral non-typeable Haemophilus influenzae (NTHi) vaccine in chronic obstructive pulmonary disease (COPD): severe COPD, moderate-severe exacerbations as end-point and a threshold prevalence of NTHi in the study population. More data are needed to confirm parameters that influence clinical outcomes.

AIMS: The primary aim was to determine the efficacy of an oral NTHi vaccine (HI-164OV) in reducing the rate of exacerbations requiring systemic corticosteroids or hospitalisation in COPD. Secondary aims included effect on the proportion of patients experiencing such exacerbations, severity of infections and quality of life (St George Respiratory Questionnaire for COPD patients (SGRQ-C)).

METHODS: This multi-centre, double-blind, placebo-controlled study was conducted at 21 Australian sites for 9 months in 2011.

RESULTS: Three-hundred and twenty subjects with COPD, FEV1 <60% predicted and ≥1 moderate-severe exacerbations in the previous 12 months were recruited. The primary and secondary end-points for the intention-to-treat population aged 40-88 years were not achieved, and only 5% of subjects had an H. influenzae-positive sputum sample. Subsequent exploratory analysis of patients <65 years (91 subjects) indicated protection with respect to the primary and most of the secondary end-points, with SGRQ-C symptom scores lower at 3 and 6 months.

CONCLUSION: Patients aged 40-88 years with moderate to severe COPD and low rates of H. influenzae-positive sputum were not protected against exacerbations by HI-1640V. Further studies are needed to confirm protection in subjects aged <65 years. Older age and low colonisation rates appear to affect adversely response to this vaccine.