Asthma: no clear role for influenza vaccination

Clinical bottom line (level 1a-)

  1. Patients with asthma who receive influenza vaccination compared with placebo are not clearly less likely to have an exacerbation over the next few months, but are more likely to have one in the next week (NN T = 33 at 4 days) ..
Cates et al: Cochrane Library 2000; 4 : -
Expires October 2003

The study

Systematic review of all randomised controlld trials of
  • Patients: asthma
  • Intervention: influenza vaccination compared with placebo or no treatment
  • Outcome: asthma exacerbations, adverse effects, hospital admission, death, pulmonary function

    Articles found in ?all languages using Cochrane Airways Group register (derived from Medline, Embase, CINAHL, CENTRAL, and hand-searching 20 respiratory journals, - July 2000 (search terms: ) and searching bibliographies of retrieved articles

    Selection criteria: 2 independent reviewers
    Appraisal criteria: 2 independent reviewers using Jadad criteria
    Articles excluded if:
    • children aged under 2
    • patients with COPD


    9 studies found. The included trials covered a diverse range of patients, settings and types of influenza vaccination so data were not pooled.

    The evidence

    Outcome Time to outcome CER EER RRR
    (95% CI)    		 ARR
    (95% CI)    		 NNH
    (95% CI)
    split virus or surface antigen vaccine v. placebo: asthma exacerbation 4 days 3
    (1.15%)    		 11
    (4.21%)    		 73%
    (3% to 92%)    		 3.07%
    (0.31% to 5.83%)    		 33
    (17 to 330)

    • Excluding patients with an upper respiratory tract infection from the above meta-analysis led to a non-significant difference for exacerbations between the two groups.
    • 1 study assess the protective effect of influenza vaccination, but only 1 confirmed case of influenza occured in both arms of the study, so no conclusions could be drawn.
    • No vaccine type was found to be clearly better than another.

    Citation

    1. Cates CJ, Jefferson TO, Bara AI: vaccines for preventing influenza in people with asthma. Cochrane Library 2000; 4 : -
    Search Terms: asthma in Cochrane Library
    Contributor: Chris Ball, October 2001
    Reviewer:

    Clinical Question.
    Patient asthma
    Intervention or Exposure influenza vaccination
    Comparison placebo or no treatment
    Outcome asthma exacerbation, adverse effects