インフルエンザワクチンが効果に関する文献

〇ワクチンが効果があったとする文献 Effectiveness of Influenza Vaccine in the Community-Dwelling Elderly Kristin L. Nichol, M.D., M.P.H., M.B.A., James D. Nordin, M.D., M.P.H., David B. Nelson, Ph.D., John P. Mullooly, Ph.D., and Eelko Hak, Ph.D. N Engl J Med 2007; 357:1373-1381 BACKGROUND Reliable estimates of the effectiveness of influenza vaccine among persons 65 years of age and older are important for informed vaccination policies and programs. Short-term studies may provide misleading pictures of long-term benefits, and residual confounding may have biased past results. This study examined the effectiveness of influenza vaccine in seniors over the long term while addressing potential bias and residual confounding in the results. Full Text of Background... METHODS Data were pooled from 18 cohorts of community-dwelling elderly members of one U.S. health maintenance organization (HMO) for 1990–1991 through 1999–2000 and of two other HMOs for 1996–1997 through 1999–2000. Logistic regression was used to estimate the effectiveness of the vaccine for the prevention of hospitalization for pneumonia or influenza and death after adjustment for important covariates. Additional analyses explored for evidence of bias and the potential effect of residual confounding... RESULTS There were 713,872 person-seasons of observation. Most high-risk medical conditions that were measured were more prevalent among vaccinated than among unvaccinated persons. Vaccination was associated with a 27% reduction in the risk of hospitalization for pneumonia or influenza (adjusted odds ratio, 0.73; 95% confidence interval [CI], 0.68 to 0.77) and a 48% reduction in the risk of death (adjusted odds ratio, 0.52; 95% CI, 0.50 to 0.55). Estimates were generally stable across age and risk subgroups. In the sensitivity analyses, we modeled the effect of a hypothetical unmeasured confounder that would have caused overestimation of vaccine effectiveness in the main analysis; vaccination was still associated with statistically significant — though lower — reductions in the risks of both hospitalization and death. CONCLUSIONS During 10 seasons, influenza vaccination was associated with significant reductions in the risk of hospitalization for pneumonia or influenza and in the risk of death among community-dwelling elderly persons. Vaccine delivery to this high-priority group should be improved. After adjusting for bias in meta-analysis seasonal influenza vaccineremains effective in community-dwelling elderly* Maryam Darvishiana,b, Giedre Gefenaitea,b, Rebecca M. Turnerc, Petros Pechlivanogloua,d,Wim Van der Hoeke, Edwin R. Van den Heuvelb, Eelko Hak Journal of Clinical Epidemiology 67 (2014) 734-744 Abstract Objective: To compare the performance of the bias-adjusted meta-analysis to the conventional meta-analysis assessing seasonal influenzavaccine effectiveness among community-dwelling elderly aged 60 years and older.Study Design and Setting: Systematic literature search revealed 14 cohort studies that met inclusion and exclusion criteria. Laboratory-confirmed influenza, influenza-like illness, hospitalization from influenza and/or pneumonia, and all-cause mortality were study outcomes. Potential biases were identified using bias checklists. The magnitude and uncertainty of biases were assessed by expert opinion. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using random effects model. Results: After incorporating biases, overall effect estimates regressed slightly toward no effect, with the largest relative difference between conventional and bias-adjusted ORs for laboratory-confirmed influenza (OR, 0.18; 95% CI: 0.01, 3.00 vs. OR, 0.23; 95% CI: 0.03,2.04). In most of the studies, CIs widened reflecting uncertainties about the biases. The between-study heterogeneity reduced considerably with the largest reduction for all-cause mortality (I2 5 4%, P 5 0.39 vs. I2 5 91%, P ! 0.01). Conclusion: This case study showed that after addressing potential biases influenza vaccine was still estimated effective in preventing hospitalization from influenza and/or pneumonia and all-cause mortality. Increasing the number of assessors and incorporating empirical evidence might improve the new bias-adjustment method.

〇インフルエンザワクチンが効果がないとする文献 前橋レポート　1980年 『前橋レポート』は、1990年前半にインフルエンザの集団予防接種が廃止されるきっかけとなった。 1979 年の初冬、群馬県の前橋市医師会が集団予防接種の中止に踏み切った。そのきっかけは予防接種後の副作用（痙攣発作）だった。予防接種の中止でインフルエンザ流行にどのような変化があるのか、詳細な調査を始めた。 予防接種中止が正しかったのか、間違っていたのかを検証した。５年間の調査結果では、ワクチンを接種してもしなくても、インフルエンザの流行状況には変化がなかった。この調査をきっかけに、集団予防接種を中止することになり、1994 年に予防接種は 任意接種に変わった。

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