Haemophilus influenzae oral whole cell vaccination for preventing acute exacerbations of chronic bronchitis

Acute bronchitis leading to ongoing exacerbations is a serious condition predisposed to by viruses or bacteria. It can be fatal. Antibiotic therapy has not been particularly useful in clearing bacteria such as nontypeable Haemophilus influenzae (NTHi) because they colonise the upper respiratory tract. An oral NTHi vaccine has been developed to protect against recurrent acute episodes in chronic bronchitis.

To assess the effects of an oral whole cell nontypeable Haemophilus influenzae (NTHi) vaccine in protecting against recurrent acute episodes in chronic bronchitis.

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (issue 1, 2003); MEDLINE (1966 to 2003); EMBASE (1990 - 2003); Extramed (1994 to 2003); ISI Current Contents (1993 to 2003); Carl Uncover (1988 to 2003) and contacted investigators of the studies.

Randomised trials comparing the effects of an oral monobacterial NTHi vaccine on patients with recurrent acute exacerbations of chronic bronchitis were included when there was overt matching of the vaccine and placebo groups on clinical grounds.

Three reviewers extracted data and assessed trial quality independently from original records and publications for incidence and severity of bronchitis episodes and carriage rate of nontypeable Haemophilus influenzae measured in the upper respiratory tract every three months following vaccination.

Six trials were included in the study with a total of 440 participants. Oral vaccination using a monobacterial whole cell killed nontypeable Haemophilus influenzae significantly reduced the incidence of bronchitic episodes at three months after vaccination (Poisson rate ratio 0.666; 95% confidence interval [CI] 0.500, 0.887; p = 0.005) and perhaps at six months after vaccination (Poisson rate ratio 0.831; 95% CI 0.669, 1.031; p = 0.093). The effect had disappeared by nine months. The severity of exacerbations in the treatment group, as measured by requirement to prescribe antibiotics, was likewise reduced by 58% at three months (Peto odds ratio = 0.42; 95% CI 0.16, 1.13), and by 65% at six months (Peto odds ratio = 0.35; 95% CI 0.16, 0.75).

Vaccination, in the autumn, of patients with recurrent acute exacerbations of chronic bronchitis reduced the number and severity of exacerbations over the winter months. A large clinical trial to assess longer term prognosis is needed.