Table 4

Vaccination effects on the health system (the employer perspective)

Review IDPopulationDays off workReview authors’ conclusions
No. of studies (participants)Mean difference (days)On efficacyFor policy
Ng and Lai12HCW2 (540)–0.08 (95% CI –0.19 to 0.02) (third study not included in meta-analysis)‘No definitive conclusion on the effectiveness of influenza vaccinations in HCWs’‘Further research is necessary to evaluate whether annual vaccination is a key measure to protect HCWs’
Burls et al13HCW3 (967)Statistically significant difference in only one of the three studies (MD 0.4 days, p=0.02)‘Vaccination was highly effective’‘Effective implementation should be a priority’*
Demicheli et al19Healthy adults4 (3726)Good match—three studies (2596), MD=−0.09 (−0.19 to 0.02)
Matching absent/unknown—one study (1130), MD=0.09 (0.00 to 0.18)
‘A modest effect on time off work’‘No evidence for the usage of vaccination against influenza in healthy adults as a routine public health measure’†
Michiels et al14Healthy adultsNot statedNot stated (refers to Jefferson 2010)None statedNone stated
Ferroni and Jefferson16Healthy adults1 meta-analysis including 5 studies (5393)Good match—0.21
Matching absent/unknown—0.09 (refers to Jefferson 2010)
‘May be marginally more effective than placebo’None stated
  • *This conclusion may be influenced by the reported effects on vaccine efficacy and protecting patients in tables 2 and 3, respectively.13

  • †This conclusion is influenced by the additional findings of no demonstrable effect on complications such as pneumonia or transmission.19

  • HCW, healthcare worker; MD, mean difference.