Efficacy of combined influenza and 23-valent pneumococcal polysaccharide vaccines in chronic smokers

Abstract

Background Chronic smokers are at risk of premature death associated with underlying pulmonary or cardiovascular diseases. Dual influenza and pneumococcal vaccination has been shown to prevent death and hospitalization secondary to pulmonary or cardiovascular diseases in elderly persons. Its effect in chronic smokers remained unknown.

Methods This is a prospective randomized open-labeled trial conducted from April 2010 to March 2013, comprising adult patients aged less than 50 years who were chronic smokers. Subjects were randomly assigned into 4 groups. Group 1 (study group) patients received both trivalent influenza vaccine (TIV) and the 23-valent polysaccharide pneumococcal vaccine (PPV). There were 3 control groups: Group 2 patients received the TIV only. Group 3 patients received the PPV only and Group 4 patients did not receive any vaccines. The TIV used was the Vaxigrip® (Sanofi Pasteur, France) and the PPV used was the Pneumovax®23 (Merck, USA). All enrolled patients were follow-up for 24 months post vaccination. Patient details, Charlson comorbidity index, medications, subsequent hospitalization, diagnosis and mortality were recorded and analyzed.

Results A total of 1006 subjects were enrolled and completed the study (Group PPV+TIV: 250; Group TIV: 254, Group PPV: 250 and Group None: 259). The baseline demographics and Charlson comorbidity index were similar among subjects in the 4 groups. The median age was 48 years and 85.9% were male patients. Significantly fewer subjects who received the dual vaccination (Group PPV+TIV) were hospitalized (p<0.001), with shorter mean length of stay (p<0.001), and less frequent hospitalization (p<0.001) for cardiovascular or respiratory diseases than no vaccination (Group None) or single vaccination (Group TIV and Group PPV). Multivariate analysis demonstrated that dual vaccination with PPV + TIV was the only independent factor associated with reduced risk of hospitalization (p<0.001; relative risk 0.288; 95% CI 0.101-0.154). There was no difference in mortality rate among the groups. Both vaccinations were well tolerated and no serious adverse events were reported.

Conclusion Dual influenza and pneumococcal vaccinations prevented chronic smokers against hospitalization secondary to pulmonary or cardiovascular causes. Annual influenza and a single pneumococcal vaccination should be promoted among chronic smokers.