Despite the almost universal recommendation that people with chronic obstructive pulmonary disease (COPD) should receive an annual influenza vaccination, very few randomised controlled trials have evaluated the effect of influenza vaccination in these patients. This review looks at six studies in COPD patients and a further five in elderly or high risk patients, a proportion of whom had chronic lung disease. It shows that there is now some evidence from randomised trials that inactivated influenza vaccine indeed decreases "flare ups" of COPD, especially those that are related to the influenza virus itself. The inactivated influenza virus vaccine is given intramuscularly and is associated with an increase in local side effects such as pain at the site of injection. This is short-lived, not serious and is outweighed by the long term benefit of the vaccine. The inactivated virus vaccine does not cause influenza or any significant worsening of COPD.
It appears, from the limited number of studies performed, that inactivated vaccine reduces exacerbations in COPD patients. The size of effect was similar to that seen in large observational studies, and was due to a reduction in exacerbations occurring three or more weeks after vaccination, and due to influenza. There is a mild increase in transient local adverse effects with vaccination, but no evidence of an increase in early exacerbations.
Influenza vaccinations are currently recommended in the care of people with COPD, but these recommendations are based largely on evidence from observational studies with very few randomised controlled trials (RCTs) reported. Influenza infection causes excess morbidity and mortality in COPD patients but there is also the potential for influenza vaccination to cause adverse effects or not to be cost effective.
To evaluate the evidence from RCTs for a treatment effect of influenza vaccination in COPD subjects. Outcomes of interest were exacerbation rates, hospitalisations, mortality, lung function and adverse effects.
We searched the Cochrane Airways Group Specialised Register of trials, and reference lists of articles. References were also provided by a number of drug companies we contacted. The latest search was carried out in May 2010.
RCTs that compared live or inactivated virus vaccines with placebo, either alone or with another vaccine in persons with COPD. Studies of people with asthma were excluded.
Two reviewers extracted data. All entries were double checked. Study authors and drug companies were contacted for missing information.
Eleven trials were included but only six of these were specifically performed in COPD patients. The others were conducted on elderly and high-risk individuals, some of whom had chronic lung disease. Inactivated vaccine in COPD patients resulted in a significant reduction in the total number of exacerbations per vaccinated subject compared with those who received placebo (weighted mean difference (WMD) -0.37, 95% confidence interval -0.64 to -0.11, P = 0.006). This was due to the reduction in "late" exacerbations occurring after three or four weeks (WMD -0.39, 95% CI -0.61 to -0.18, P = 0.0004). In Howells 1961, the number of patients experiencing late exacerbations was also significantly less (odds ratio 0.13, 95% CI 0.04 to 0.45, P = 0.002). Both Howells 1961 and Wongsurakiat 2004 found that inactivated influenza vaccination reduced influenza -related respiratory infections (WMD 0.19, 95% CI 0.07 to 0.48, P = 0.0005). In both COPD patient and in elderly patients (only a minority of whom had COPD), there was a significant increase in the occurrence of local adverse reactions in vaccinees, but the effects were generally mild and transient. There was no evidence of an effect of intranasal live attenuated virus when this was added to inactivated intramuscular vaccination. The studies are too small to have detected any effect on mortality.
An updated search conducted in September 2001did not yield any further studies. A search in 2003 yielded two further reports of the same eligible study Gorse 2003. A search in 2004 yielded two reports of the another eligible study Wongsurakiat 2004. The author informed us of another report of the same study Wongsurakiat 2004/2. An update search in May 2010 did not identify any new studies for consideration.