Effectiveness of Influenza Vaccine for Children: Reconsidered

Abstract

Infectious Diseases| May 01 2005 Effectiveness of Influenza Vaccine for Children: Reconsidered AAP Grand Rounds (2005) 13 (5): 51–52. https://doi.org/10.1542/gr.13-5-51 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Effectiveness of Influenza Vaccine for Children: Reconsidered. AAP Grand Rounds May 2005; 13 (5): 51–52. https://doi.org/10.1542/gr.13-5-51 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search toolbar search search input Search input auto suggest filter your search All PublicationsAll JournalsAAP Grand RoundsPediatricsHospital PediatricsPediatrics In ReviewNeoReviewsAAP NewsAll AAP Sites Search Advanced Search Topics: influenza vaccines Source: Jefferson T, Smith S, Demicheli V, et al. Assessment of the efficacy and effectiveness of influenza vaccines in healthy children: systematic review. Lancet. 2005;365:773–780. To assess the efficacy and effectiveness of influenza vaccines in children up to 16 years of age, researchers from Oxford reviewed data from randomized trials, cohort and case-control studies in which the efficacy of vaccines against influenza, effectiveness of vaccines against influenza-like illness, or both, with placebo or no intervention, were compared. For their meta-analysis, 24 studies met inclusion criteria. The efficacy of live attenuated vaccines was estimated to be 79% and their effectiveness 38% in children over 2 years. Inactivated vaccines had 65% efficacy and 28% effectiveness in children older than 2 years; in children 2 years old and younger, the efficacy of vaccines was similar to placebo and no evidence was found of their effectiveness. Vaccines were somewhat effective at reducing school absence, but there was no evidence for reduction in mortality, admissions, serious complications, or secondary cases of influenza among children less than 16 years old. The authors conclude that influenza vaccines, especially 2-dose live attenuated vaccines, are efficacious in children older than 2 years, although their effectiveness is low. In children age 2 years or younger, inactivated vaccine efficacy was no better than that of placebo and its effectiveness could not be documented. Therefore, the authors conclude that immunization of very young children is not supported by the findings of this meta-analysis. Dr. Dubik has disclosed no financial relationships relevant to this commentary. Differences between efficacy and effectiveness are to be expected. Ordinarily, vaccine efficacy estimates are based on results obtained in clinical trials, while vaccine effectiveness estimates are based on the performance of immunization in “real world” practice. In the above paper, the authors use efficacy to refer to influenza vaccines’ efficacy in preventing outcomes associated with laboratory-confirmed influenza infection, and effectiveness to refer to the vaccines’ effectiveness in preventing non-specific clinical syndromes associated with influenza. Influenza vaccines are formulated to elicit antibodies to the specific antigenic types of influenza A and B predicted to be circulating during each influenza season. These vaccines cannot prevent morbidity from the multitude of other causes of influenza-like illnesses. The authors used strict inclusion criteria for their meta-analysis. For example, it did not include studies that used the hepatitis A vaccine1,2 or the hepatitis B vaccine3 as the control or otherwise failed to use a true placebo.4,5 As influenza immunization is now the standard of care for United States children at high risk for complicated disease, large, placebo-controlled, randomized trials that would meet the criteria for inclusion in this meta-analysis are no longer practical. So, we have a catch-22. Public health policy, like clinical decisions, is based on the best evidence available. Rarely is this evidence beyond critique. However, decisions must be made, for indecision is itself a decision. It is a fundamental tenet of science that we question current practice and critically examine... You do not currently have access to this content.