Online link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5415833/

Systematic Review

Background

Influenza is a frequent cause of exacerbations of chronic obstructive pulmonary disease (COPD). Exacerbations are associated with worsening of the airflow obstruction, hospitalization, reduced quality of life, disease progression, death, and ultimately, substantial healthcare-related costs. Despite longstanding recommendations to vaccinate vulnerable high-risk groups against seasonal influenza, including patients with COPD, vaccination rates remain sub-optimal in this population.

Methods

We conducted a systematic review to summarize current evidence from randomized controlled trials (RCTs) and observational studies on the immunogenicity, safety, efficacy, and effectiveness of seasonal influenza vaccination in patients with COPD. The selection of relevant articles was based on a three-step selection procedure according to predefined inclusion and exclusion criteria. The search yielded 650 unique hits of which 48 eligible articles were screened in full-text.

Results

Seventeen articles describing 13 different studies were found to be pertinent to this review. Results of four RCTs and one observational study demonstrate that seasonal influenza vaccination is immunogenic in patients with COPD. Two studies assessed the occurrence of COPD exacerbations 14 days after influenza vaccination and found no evidence of an increased risk of exacerbation. Three RCTs showed no significant difference in the occurrence of systemic effects between groups receiving influenza vaccine or placebo. Six out of seven studies on vaccine efficacy or effectiveness indicated long-term benefits of seasonal influenza vaccination, such as reduced number of exacerbations, reduced hospitalizations, and outpatient visits, and decreased all-cause and respiratory mortality.

Conclusions

Additional large and well-designed observational studies would contribute to understanding the impact of disease severity and patient characteristics on the response to influenza vaccination. Overall, the evidence supports a positive benefit-risk ratio for seasonal influenza vaccination in patients with COPD and supports current vaccination recommendations in this population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-017-0420-8) contains supplementary material, which is available to authorized users.

–          This article was published in 2017 and its focus was to find out the effectiveness of seasonal influenza vaccination in patients with COPD.

–          This systemic review included 17 studies: 7 RCTs, 2 prospective cohort studies, 6 retrospective cohort studies and 2-self-controlled case studies with a total population size of 174,145 patients.

–          These studies were performed across different influenza seasons in Australia, Taiwan, India, Spain, UK, and US.

–          In this systematic review, they excluded studies that included patients with a mix of pulmonary diseases and if results were not presented separately for COPD.

–          Two of the 7 RCTs specifically looked at COPD exacerbations after influenza vaccination and compared that group of patients to the control group which were patients with no influenza vaccination. Neither study showed evidence of an increased risk of exacerbation up to 14 days post vaccination.

–          Spirometry was also performed in those patients who received influenza vaccination and those who did not. Spirometry readings did not show significant changes after vaccination when compared to the non-vaccinated group. There was no significant difference between the two groups.

–          Two different RCTs reported local symptoms occurring where the influenza vaccine was given. Those symptoms were pain at the site of injection, itching and swelling. All of the reported cases were non-life threatening.

–          When it came to constitutional symptoms, 3 RCTs concluded there was no significant difference between the group that received the vaccine vs the placebo group. The more commonly reported symptoms in both groups were: myalgia and headaches.

–          One prospective study reported that after one year of follow-ups, vaccinated patients experienced significantly less episodes of influenza-related acute respiratory than unvaccinated patients, (4/62 patients in those who got the vaccine vs 17/ 63 patients in those who didn’t). Vaccinated patients also had significantly fewer outpatient visits than those who were not vaccinated in that 1 year follow up (2/63 in those who did receive the vaccine vs 12/63 in those who didn’t receive the vaccine.)

–          In the study that was conducted in Spain, they found no significant difference between those who received the vaccine and those who didn’t in mortality rate.

–          Retrospective study in Taiwan which had more than 25,000 pts, concluded that seasonal influenza vaccination in elderly pts with COPD, significantly reduced exacerbation than those who didn’t receive the vaccine.

–          Almost all studies included in this article also reported less hospitalization rates for those COPD patients who received influenza vaccine vs those COPD patients who did not.