The effectiveness of seasonal influenza vaccination in health care workers : a systematic review

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The effectiveness of seasonal influenza vaccination in health care workers : a systematic review


Author: Ng, Ngai-ming Anthony
Title: The effectiveness of seasonal influenza vaccination in health care workers : a systematic review
Degree: M.Sc.
Year: 2010
Subject: Hong Kong Polytechnic University -- Dissertations
Influenza -- Vaccination -- China -- Hong Kong
Medical personnel -- Health and hygiene -- China -- Hong Kong
Influenza vaccines -- China -- Hong Kong
Department: Faculty of Health and Social Sciences
Pages: ix, 101 leaves : ill. ; 30 cm.
InnoPac Record:
Abstract: Background: Various health authorities have strongly recommended giving health care workers (HCWs) an annual influenza vaccination as a key measure to protect HCWs and patients at risk from influenza infections. There have been reviews evaluating the effectiveness of vaccinations of different groups of patients, but none of these have focused on the effectiveness of vaccinating HCWs. The objectives of this systematic review are to determine the effect of seasonal influenza vaccinations in reducing laboratory confirmed seasonal influenza infections, influenza-like illnesses (ILI), working days lost among vaccinated HCWs, and associated adverse effects after vaccination. Methods: Twenty-four health care related databases, internet resources, reference lists, and the bibliographies of all of the retrieved articles were examined. All of the searches were performed up to 30th April 2009. All randomized controlled trials (RCTs) compared the effectiveness of any kind of seasonal influenza vaccine among all groups of HCWs with a placebo/vaccine other than the influenza vaccine/no intervention would be included in the review. The effectiveness of the seasonal influenza vaccine were measured by the occurrence of (1) laboratory confirmed influenza infections; (2) ILI; (3) working days lost, and (4) adverse effects after vaccination. The investigator assessed the quality of the methodology and the extracted data from the published reports of the trials included in this review. The authors of these studies were also contacted for additional information when necessary. Results: The quality of the methodologies used in two of the included trials was rated as high and one was rated as moderate. In all three of the included trials the trivalent inactivated parenteral seasonal influenza vaccine was used and the trials were conducted in hospital settings. A collective total of 967 HCWs were involved in the studies. The meta-analytic technique could only be employed on the outcome of working days lost because not all outcomes were reported in the same way and some information for a meta-analysis was missing. The results of the remaining outcomes came from individual trials. The available data suggested that the seasonal influenza vaccines were 88% (95% confidence interval [CI]: 59% to 96%; p=0.0005) effective against laboratory confirmed influenza infections among HCWs. However, the vaccinations could not reduce the incidence of ILI (relative risk [RR]: 1.07; 95% CI: 0.62 to 1.85; p=0.81), the number of ILI episodes (rate ratio: 1.14; 95% CI: 0.15, 8.52; p=0.9); days with ILI symptoms (mean difference: -0.12 days; 95% CI: -0.3 days to 0.06 days; p=0.18), or working days lost among the vaccinated HCWs (the pooled mean difference in two trials: -0.08 days; 95%CI: -0.19 days to 0.02 days; p=0.11). Meanwhile, the amount of information from the included trials was inadequate for comparisons to be made of the adverse effects on HCWs after receipt seasonal influenza vaccination. Conclusion: There is a limited amount of evidence suggesting that receiving seasonal influenza vaccination could reduce laboratory confirmed influenza infections in HCWs. No evidence can be found of seasonal influenza vaccinations significantly reducing the incidence of influenza, number of ILI episodes, days with ILI symptoms, or amount of sick leave taken among vaccinated HCWs. There is insufficient data to assess the adverse effects after vaccination. Due to the small number of included trials, and absent the availability of more RCTs addressing the clinical benefits of seasonal influenza vaccine in HCWs, it was difficult to reach a definitive conclusion on the effectiveness of seasonal influenza vaccinations in HCWs.

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