Health Evidence Bulletins - Wales
Team Leader: Dr Michael Burr Date of completion: 5/1/98

The contents of this bulletin are likely to be valid for approximately one year, by which time significantly new research evidence may become available

7. Influenza

(Users are advised to consult the supporting evidence for a consideration of all the implications of a recommendation)

The Statements The Evidence
7a. Immunisation reduces the incidence of influenza and its complications in infants (acute otitis media) i, older children (clinical influenza, seroconversions, positive cultures)ii, adults (clinical influenza, seroconversions, positive cultures, days off work)ii,iii and the elderly (hospital admission, pneumonia, death)iv,v. The Joint Committee on Vaccination and Immunisation recommends selective immunisation of high-risk groups (eg. people with diabetes or chronic respiratory or renal conditions), residents of nursing homes, old people's homes and other long-stay facilities where rapid spread is likely to follow introduction of infection. Details are set out in a Chief Medical Officer's letter issued annually vi.

(Health gain notation - 1 "beneficial")







i. Clements DA, Langdon L, Bland C, Walter E. Influenza A vaccine decreases the incidence of otitis media in 6- to 30-month old children in day care. Archives of Pediatric and Adolescent Medicine 1995; 149: 1113-1117
(Type II evidence - randomised controlled trial);
ii. Edwards KM, Dupont WD, Westrich MK, Plummer WD, Palmer PS, Wright PF. A randomized controlled trial of cold-adapted and inactivated vaccines for the prevention of influenza A disease. Journal of Infectious Diseases 1994; 169: 68-76.
(Type II evidence - randomised controlled trial);
iii. Nichol KL, Lind A, Margolis KL et al. The effectiveness of vaccination against influenza in healthy, working adults. New England Journal of Medicine 1995; 333: 889-893
(Type II evidence - randomised controlled trial);
iv. Puig Barberà J, Márquez Calderón S. Efectividad de la vacunación antigripal en los ancianos. Una revisión crítica de la bibliografía. Medicina Clinica (Barc) 1995; 105: 645-648
(Type I evidence - systematic review);
v. Gross PA, Hermogenes AW, Sacks HS, Lau J, Levandowski RA. The efficacy of influenza vaccine in elderly persons: a meta-analysis and review of the literature. Annals of Internal Medicine 1995, 123: 518-527
(Type I evidence - systematic review and meta-analysis);
caveat: The evidence in iv. and v. comprises several observational studies, but only one randomised controlled trial.
vi. CMO’s Update 15. Cardiff: Welsh Office, August 1997
7b. Two related antiviral drugs, amantadine and its derivative rimantadine, have been shown to be effective in the prevention and treatment of influenza A infections but there is, as yet, no general agreement on how to use them. One of the major factors restricting their value is the lack of rapid diagnostic methods. For now, they probably have a limited use as adjuncts to vaccines in preventing influenza A infections and in the treatment of acute infectionsi.
(Health gain notation - 3 "trade-off between beneficial and adverse effects")
i. Wintermeyer SM, Nahata MC. Rimantadine: a clinical perspective. Annals of Pharmacotherapy 1995; 29: 299-310
(Type I evidence - systematic review)

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