Question

Do influenza vaccines reduce episodes of respiratory illness or death in people with chronic obstructive pulmonary disease (COPD)?

Background

COPD is an umbrella term used to describe progressive lung diseases, including emphysema, chronic bronchitis, and refractory (non-reversible) asthma. The disease is characterized by increasing breathlessness. Despite the almost universal recommendation that people with COPD should receive an annual influenza vaccination, very few randomised controlled trials (studies in which a number of similar people are randomly assigned to two (or more) groups to test a specific drug, treatment or other intervention) have evaluated the effect of this treatment. Influenza vaccines may be produced with an inactivated virus (small particles of the virus wall) or live attenuated virus (reduced power but still alive).

To try to answer our question, we conducted a detailed search for studies from around the world that investigated the use of influenza vaccines for people with COPD.

Study characteristics

We included six studies with 2469 participants with COPD, and a further five studies with 4281 older or high risk participants, a proportion of whom had chronic lung disease.

Key resuIts

We found some moderate-quality evidence that inactivated influenza vaccine did decrease ‘flare ups’ of COPD, especially those that are related to the influenza virus itself. The inactivated influenza virus vaccine was given as an injection in the muscle, and was associated with an increase in local side effects (such as pain) at the site of injection, which were short-lived. The inactivated virus vaccine did not cause influenza, or any significant worsening of COPD. Adding a live attenuated virus to the inactivated virus did not add any further protection for the participants.

Quality of the evidence

The evidence was of moderate quality. There have been no new trials since 2004. We conducted the last literature search in December 2017.