Here are some studies that does not conclude that vaccine is effective against influenza:
Influenza Vaccination in Children with Asthma
Herman J. Bueving, Roos M. D. Bernsen, Johan C. de Jongste, Lisette W. A. van Suijlekom-Smit,
Guus F. Rimmelzwaan, Albert D. M. E. Osterhaus, Maureen P. M. H. Rutten-van Molken,
Siep Thomas, and Johannes C. van der Wouden
“We determined whether influenza vaccination is more effective than placebo in 6–18-year-old children with asthma.
Primary outcome was the number of asthma exacerbations associated with virologically proven influenza infection.”
Three hundred forty-nine children were assigned placebo, and 347 were assigned vaccine.
We conclude that influenza vaccination did not result in a significant reduction of the number, severity, or duration of asthma exacerbations caused by influenza.
Vaccines for preventing influenza in healthy adults.
Jefferson T, Di Pietrantonj C, Rivetti A, Bawazeer GA, Al-Ansary LA, Ferroni E.
OBJECTIVES: Identify, retrieve and assess all studies evaluating the effects of vaccines against influenza in healthy adults.
SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2010, issue 2), MEDLINE (January 1966 to June 2010) and EMBASE (1990 to June 2010).
SELECTION CRITERIA:
Randomised controlled trials (RCTs) or quasi-RCTs comparing influenza vaccines with placebo or no intervention in naturally-occurring influenza in healthy individuals aged 16 to 65 years. We also included comparative studies assessing serious and rare harms
MAIN RESULTS:
We included 50 reports. Forty (59 sub-studies) were clinical trials of over 70,000 people.
In the relatively uncommon circumstance of vaccine matching the viral circulating strain and high circulation, 4% of unvaccinated people versus 1% of vaccinated people developed influenza symptoms
The corresponding figures for poor vaccine matching were 2% and 1%. These differences were not likely to be due to chance.
Vaccination had a modest effect on time off work and had no effect on hospital admissions or complication rates.
Inactivated vaccines caused local harms and an estimated 1.6 additional cases of Guillain-Barré Syndrome per million vaccinations.
AUTHORS' CONCLUSIONS:
Influenza vaccines have a modest effect in reducing influenza symptoms and working days lost. There is no evidence that they affect complications, such as pneumonia, or transmission.
WARNING: This review includes 15 out of 36 trials funded by industry. An earlier systematic review of 274 influenza vaccine studies published up to 2007 found industry funded studies were published in more prestigious journals and cited more than other studies independently from methodological quality and size.
Studies funded from public sources were significantly less likely to report conclusions favorable to the vaccines. The review showed that reliable evidence on influenza vaccines is thin but there is evidence of widespread manipulation of conclusions and spurious notoriety of the studies.
Influenza vaccine effectiveness among children 6 to 59 months of age during 2 influenza seasons: a case-cohort study.
Szilagyi PG, Fairbrother G, Griffin MR, Hornung RW, Donauer S, Morrow A, Altaye M, Zhu Y, Ambrose S, Edwards KM, Poehling KA, Lofthus G, Holloway M, Finelli L, Iwane M, Staat MA; New Vaccine Surveillance Network.
OBJECTIVE:
To measure vaccine effectiveness (VE) in preventing influenza-related health care visits among children aged 6 to 59 months during 2 consecutive influenza seasons.
DESIGN:
We compared vaccination status of laboratory-confirmed influenza cases with a cluster sample of children from a random sample of practices in 3 counties (subcohort) during the 2003-2004 and 2004-2005 seasons.
PARTICIPANTS:
Children aged 6 to 59 months seen in inpatient/ED or outpatient clinic settings for acute respiratory illnesses and community-based subcohort comparison. Main Exposure Influenza vaccination.
RESULTS:
However, significant influenza VE could not be demonstrated for any season, age, or setting after adjusting for county, sex, insurance, chronic conditions recommended for influenza vaccination, and timing of influenza vaccination
CONCLUSION:
In 2 seasons with suboptimal antigenic match between vaccines and circulating strains, we could not demonstrate VE in preventing influenza-related inpatient/ED or outpatient visits in children younger than 5 years. Further study is needed during years with good vaccine match.
Influenza vaccination for healthcare workers who work with the elderly – Feb 2010
Department of Medicine, University of Calgary, UCMC, Alberta, Canada.
OBJECTIVES: To identify studies of vaccinating HCWs and the incidence of influenza, its complications and influenza-like illness (ILI) in individuals >/= 60 in long-term care facilities (LTCFs).
Two authors independently extracted data and assessed risk of bias.
AUTHORS' CONCLUSIONS:
No effect was shown for specific outcomes: laboratory-proven influenza, pneumonia and death from pneumonia. An effect was shown for the non-specific outcomes of ILI, GP consultations for ILI and all-cause mortality in individuals >/= 60.
These non-specific outcomes are difficult to interpret because ILI includes many pathogens, and winter influenza contributes < 10% to all-cause mortality in individuals >/= 60. The key interest is preventing laboratory-proven influenza in individuals >/= 60, pneumonia and deaths from pneumonia, and we cannot draw such conclusions.
We conclude there is no evidence that vaccinating HCWs prevents influenza in elderly residents.
Impact of influenza vaccination on seasonal mortality in the US elderly population.
Simonsen L, Reichert TA, Viboud C, Blackwelder WC, Taylor RJ, Miller MA.
BACKGROUND:
Observational studies report that influenza vaccination reduces winter mortality risk from any cause by 50% among the elderly. Influenza vaccination coverage among elderly persons (> or =65 years) in the United States increased from between 15% and 20% before 1980 to 65% in 2001. Unexpectedly, estimates of influenza-related mortality in this age group also increased during this period. We tried to reconcile these conflicting findings by adjusting excess mortality estimates for aging and increased circulation of influenza A(H3N2) viruses.
RESULTS:
For people aged 65 to 74 years, excess mortality rates in A(H3N2)-dominated seasons fell between 1968 and the early 1980s but remained approximately constant thereafter. For persons 85 years or older, the mortality rate remained flat throughout. Excess mortality in A(H1N1) and B seasons did not change. All-cause excess mortality for persons 65 years or older never exceeded 10% of all winter deaths.
CONCLUSIONS:
We attribute the decline in influenza-related mortality among people aged 65 to 74 years in the decade after the 1968 pandemic to the acquisition of immunity to the emerging A(H3N2) virus. We could not correlate increasing vaccination coverage after 1980 with declining mortality rates in any age group. Because fewer than 10% of all winter deaths were attributable to influenza in any season, we conclude that observational studies substantially overestimate vaccination benefit.
Influenza-related mortality in the Italian elderly: no decline associated with increasing vaccination coverage.
Rizzo C, Viboud C, Montomoli E, Simonsen L, Miller MA.
We investigated trends in influenza-related mortality among the elderly population in Italy associated with increased vaccination coverage.
Using Italian vital statistics data, we studied monthly death rates for pneumonia and influenza and all-cause for persons >/=65 years of age by 5-year age groups for 1970-2001.
We studied trends in excess mortality after adjusting for population aging and analyzing separately seasons dominated by the severe A/H3N2 subtype and those dominated by other circulating influenza subtypes.
After the late 1980s, no decline in age-adjusted excess mortality was associated with increasing influenza vaccination distribution primarily targeted for the elderly.
These findings suggest that either the vaccine failed to protect the elderly against mortality (possibly due to immune senescence), and/or the vaccination efforts did not adequately target the frailest elderly.
As in the US, our study challenges current strategies to best protect the elderly against mortality, warranting the need for better controlled trials with alternative vaccination strategies.
