The review found no eligible studies for this question.
Influenza vaccine showed no clear difference in hospital admissions compared with placebo (low certainty).
Influenza vaccine showed no clear difference in mortality compared with placebo (low certainty).
Influenza vaccine may leads to higher local effects at injection site compared with placebo (low certainty).
The review found no eligible studies for this question.
It is very uncertain whether influenza vaccine changes all deaths compared with placebo (very low certainty).
Influenza vaccine showed no clear difference in fever compared with placebo (moderate certainty).
Influenza vaccine showed no clear difference in nausea compared with placebo (low certainty).
Influenza vaccine showed no clear difference in at least 1 episode of acute otitis media compared with control (low certainty).
Influenza vaccine probably leads to lower courses of antibiotics compared with control (moderate certainty).
Influenza vaccine may leads to higher fever compared with control (low certainty).
Influenza vaccine may leads to higher rhinorrhoea compared with control (low certainty).
Influenza vaccine showed no clear difference in pharyngitis compared with control (low certainty).
Inactivated parenteral influenza vaccine showed no clear difference in hospitalisations Timing of assessment: single influenza season compared with placebo or 'do nothing' (low certainty).
Inactivated parenteral influenza vaccine leads to higher fever assessed by subjective report Timing of assessment: single… compared with placebo or 'do nothing' (high certainty).
Inactivated parenteral influenza vaccine showed no clear difference in nausea or vomiting assessed by subjective report Timing of… compared with placebo or 'do nothing' (low certainty).
Inactivated influenza vaccine showed no clear difference in otitis media assessed by clinical confirmation (inspection of ear… compared with placebo or do nothing (moderate certainty).