Flu Shot Effectiveness --> RE: vaccinations

[Guest guest]

I suppose it depends on what you are trying to prevent...hospitalization or death.

I have also seen some studies in the past suggesting flu shots aren't all they are cracked up to be for the elderly, like you suggest.

My personal bias is that they may not prevent you from getting sick (if you are elderly), but might prevent you from dying.But I'm certainly no expert in the area.

Plus, so much of the effectiveness depends on getting the strains matched up in the vaccine.

But you do raise a good point.

Locke, MD

http://www.cdc.gov/MMWR/preview/mmwrhtml/rr5606a1.htm

In a case-control study conducted during 2003--2004, when the vaccine was a suboptimal antigenic match to many circulating virus strains, effectiveness for prevention of laboratory-confirmed influenza illness among adults aged 50--64 years with high risk conditions was 48%, compared with 60% for healthy adults (137). Effectiveness against hospitalization among adults aged 50--64 years with high-risk conditions was 36%, compared with 90% efficacy among healthy adults in that age range (137).

Studies using less specific outcomes, without laboratory confirmation of influenza virus infection, typically have demonstrated substantial reductions in hospitalizations or deaths among adults with risk factors for influenza complications. In a case-control study conducted in Denmark during 1999--2000, vaccination reduced deaths attributable to any cause 78% and reduced hospitalizations attributable to respiratory infections or cardiopulmonary diseases 87% (141). Benefit was reported after the first vaccination and increased with subsequent vaccinations in subsequent years (142). Among patients with diabetes mellitus, vaccination was associated with a 56% reduction in any complication, a 54% reduction in hospitalizations, and a 58% reduction in deaths (143).

Certain experts have noted that the substantial effects on morbidity and mortality among those who received influenza vaccination in these observational studies should be interpreted with caution because of the difficulties in ensuring that those who received vaccination had similar baseline health status as those who did not (90).

One meta-analysis of published studies did not determine sufficient evidence to conclude that persons with asthma benefit from vaccination (144). However, a meta-analysis that examined efficacy among persons with chronic obstructive pulmonary disease identified evidence of benefit from vaccination (145).

Older Adults

Lower postvaccination anti-influenza antibody concentrations have been reported among certain older persons compared with younger adults (139--140). A randomized trial among noninstitutionalized persons aged >60 years reported a vaccine efficacy of 58% against influenza respiratory illness but indicated that efficacy might be lower among those aged >70 years (158). Among elderly persons not living in nursing homes or similar chronic-care facilities, influenza vaccine is 30%--70% effective in preventing hospitalization for pneumonia and influenza (159,160). Influenza vaccination reduces the frequency of secondary complications and reduces the risk for influenza-related hospitalization and death among adults aged >65 years with and without high-risk medical conditions (e.g., heart disease and diabetes) (160--165). Influenza vaccine effectiveness in preventing MAARI among the elderly in nursing homes has been estimated at 20%--40%, but vaccination can be as much as 80% effective in preventing influenza-related death (165--168).

Elderly persons typically have a diminished immune response to influenza vaccination compared with young healthy adults, suggesting that immunity might be of shorter duration and less likely to extend to a second season (169). Infections among the vaccinated elderly might be related to an age-related reduction in ability to respond to vaccination rather than reduced duration of immunity.

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I didn't have access to the full article, but the report was based on 157 hospitalised cases and 639 controls (matched for age, sex and week of consultation) were interviewed.

It's difficult to tell if they were matched on health issues or not.

A case–control study of elderly patients with acute respiratory illness: Effect of influenza vaccination on admission to hospital in winter 2003–2004

R.E. Jordan, a, , J.I. Hawkerb, J.G. Ayresc, W. Tunnicliffed, P. Adabe, B. Olowokuref, J. Kaig, R.J. McManush, R. Salterh and K.K. Chenge aHealth Protection Research & Development Unit, Health Protection Agency, Department of Public Health & Epidemiology, University of Birmingham, Birmingham B15 2TT, United KingdombHealth Protection Agency, 330 High Holborn, London WC1V 7PP, United KingdomcDepartment of Environmental & Occupational Medicine, University of Aberdeen Liberty Safe Work Research Centre, Foresterhill Road, Aberdeen AB25 2ZP, United KingdomdCritical Care Unit, Selly Oak Hospital, Birmingham, United KingdomeDepartment of Public Health & Epidemiology, University of Birmingham, Birmingham B15 2TT, United KingdomfWest Midlands Regional Surveillance Unit, Health Protection Agency, 9th Floor Ladywood House, 45 son St, Birmingham B2 4DY, United KingdomgUniversity of Nottingham Graduate Medical School, Derby City General Hospital, Derby DE22 3DT, United KingdomhDepartment of Primary Care & General Practice, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom Received 14 May 2007; revised 29 August 2007; accepted 3 September 2007. Available online 21 September 2007.

Abstract

Every winter, hospitals face a large increase in emergency respiratory admissions in elderly people. A case–control study was undertaken to assess the effect of routine influenza vaccine in preventing such admissions among a cohort of UK elderly presenting with acute respiratory illness during winter 2003–2004. 157 hospitalised cases and 639 controls (matched for age, sex and week of consultation) were interviewed.

In a winter typical of levels of circulating influenza in recent years, influenza vaccine did not show a protective effect on emergency respiratory admissions overall (adjusted OR 1.2 (95%CI 0.8, 1.9). Policy makers should not rely solely on influenza vaccine routinely having a large effect on winter pressures, and should focus on additional preventive strategies.

-----Original Message-----From: [mailto: ] On Behalf Of Graham ChiuSent: Tuesday, January 08, 2008 11:40 PMTo: Subject: vaccinationsHow much times does an IMP spend on flu vaccination?http://www.sciencedirect.com/science?_ob=ArticleURL & _udi=B6TD4-4PPWK72-4 & _user=10 & _coverDate=11%2F14%2F2007 & _rdoc=6 & _fmt=summary & _orig=browse & _srch=doc-info(%23toc%235188%232007%23999749953%23673133%23FLA%23display%23Volume) & _cdi=5188 & _sort=d & _docanchor= & _ct=14 & _acct=C000050221 & _version=1 & _urlVersion=0 & _userid=10 & md5=130827524044874553032e6c7ddd7b21when there is continuing evidence for lack of benefit?--Graham Chiuhttp://www.synapsedirect.comSynapse-EMR - innovative electronic medical records system