Prevention

Why?

• Influenza vaccination does not clearly prevent exacerbations in the long-term, but may trigger one in the short-term. ^a

Patient	Treatment	Comparison	Outcome	CER	RRR (95% CI)	NNT (95% CI)
asthma a	influenza split virus or surface antigen vaccine	placebo	asthma exacerbation at 4 days	4.2%	73% (3% to 92%)	33 (17 to 330)