title: Randomised placebo-controlled crossover trial on effect of inactivated influenza vaccine on pulmonary function in asthma.
abstract: BACKGROUND
  Despite current recommendations, many people with asthma do not receive annual vaccination against influenza, partly because of concern that vaccine may trigger exacerbations. Colds can trigger exacerbations, which may be mistaken for vaccine-related adverse events. We undertook a double-blind placebo-controlled multicentre crossover study to assess the safety of influenza vaccine in patients with asthma, with allowance for the occurrence of colds.
  
  
  METHODS
  We studied 262 patients, aged 18-75 years, who recorded daily peak expiratory flow (PEF), respiratory symptoms, medication, medical consultations, and hospital admissions for 2 weeks before the first injection and until 2 weeks after the second injection. Order of injection (vaccine and placebo) was assigned randomly. There was an interval of 2 weeks between injections. The main outcome measure was an exacerbation of asthma within 72 h of injection (defined as a fall in PEF of >20%).
  
  
  RESULTS
  Among 255 participants with paired data, 11 recorded a fall in PEF of more than 20% after vaccine compared with three after placebo (McNemar's test p=0.06); a fall of more than 30% was recorded by eight after vaccine compared with none after placebo (binomial test p=0.008). However, when participants with colds were excluded, there was no significant difference in the numbers with falls of more than 20% between vaccine and placebo (six vs three; binomial test p=0.51), although the difference for PEF decreases of more than 30% approached significance (five vs none; binomial test, p=0.06). This association was confined to first-time vaccinees.
  
  
  CONCLUSIONS
  Our findings indicate that pulmonary-function abnormalities may occur as a complication of influenza vaccination. However, the risk of pulmonary complications is very small and outweighed by the benefits of vaccination.
authors.affiliation: Department of Infectious Diseases and Tropical Medicine, Leicester Royal Infirmary, UK.
authors.forename: K G
authors.initials: KG
authors.lastname: Nicholson
authors.forename: J S
authors.initials: JS
authors.lastname: Nguyen-Van-Tam
authors.forename: A H
authors.initials: AH
authors.lastname: Ahmed
authors.forename: M J
authors.initials: MJ
authors.lastname: Wiselka
authors.forename: J
authors.initials: J
authors.lastname: Leese
authors.forename: J
authors.initials: J
authors.lastname: Ayres
authors.forename: J H
authors.initials: JH
authors.lastname: Campbell
authors.forename: P
authors.initials: P
authors.lastname: Ebden
authors.forename: N M
authors.initials: NM
authors.lastname: Eiser
authors.forename: B J
authors.initials: BJ
authors.lastname: Hutchcroft
authors.forename: J C
authors.initials: JC
authors.lastname: Pearson
authors.forename: R F
authors.initials: RF
authors.lastname: Willey
authors.forename: R J
authors.initials: RJ
authors.lastname: Wolstenholme
authors.forename: M A
authors.initials: MA
authors.lastname: Woodhead
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000209:etiology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000009:adverse effects*; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D013147:Spirometry
chemical_list: D007252:Influenza Vaccines