Prevention

• influenza vaccine (preferably combined live and inactivated) ^a

Why?

• It reduces pneumonia, hospital admissions and death in elderly patients. ^b
• It causes few side effects, except sore arms. ^a

Influenza vaccination reduces pneumonia, hospital admissions and death

Patient	Treatment	Comparison	Outcome	CER	OR (95% CI)	NNT (95% CI)
elderly b	influenza vaccine	placebo	pneumonia	1.3%	0.47 (0.34 to 0.65)	150 (120 to 220)
			hospitalisation	0.79%	0.50 (0.35 to 0.72)	260 (200 to 460)
			death	1.0%	0.32 (0.24 to 0.44)	140 (130 to 170)

Intramusuclar influenza vaccination causes sore arms

Patient	Treatment	Comparison	Outcome	CER	RRR (95% CI)	NNT (95% CI)
elderly outpatient a	influenza vaccine intramuscularly	placebo intramuscularly	sore arm at	4.8%	-330% (-620% to -150%)	-6 (-9 to -5)

• Elderly patients who receive combined live and inactivated influenza A vaccines are less likely to develop influenza A, without clearly having more adverse side-effects ^a

Combined live and inactivated vaccines reduce influenza more than inactivated alone

Patient	Treatment	Comparison	Outcome	CER	RRR (95% CI)	NNT (95% CI)
elderly in long-term care facility a	combined live and inactivated vaccine	inactivated vaccine	laboratory-documented influenza A at 3 years	14%	61% (18% to 81%)	12 (7 to 43)