Re: Margaret McCartney: What use is mass flu vaccination?
In her article for BMJ titled “What use is mass flu vaccination?”, Dr. Margaret McCartney asks “why are we vaccinating so many people in whom we have no proof that it works?” Systematic reviews of influenza vaccine clinical trials have highlighted that few randomized controlled clinical studies with currently available vaccines have been conducted in adults, however estimates of vaccine efficacy in adults by these systematic reviews have differed (1-4). Some have included as negative studies those that were underpowered. Others have not included more recent trials that have been carried out for the purpose of licensure (5, 6).
In the article, McCartney conflates limited randomized clinical trial data with lack of data. It also assumes that valuable data can only come from clinical trials, which require considerable resources to conduct. With the current positive data on vaccine efficacy in younger individuals (1, 3, 7), many feel that a placebo-controlled trial in the elderly would be unethical. Well-designed, observational studies confirm influenza vaccine effectiveness in adults against influenza virus infection in the community as well as against more severe influenza disease (8, 9), however vaccine effectiveness depends on many factors including the population understudy, the degree of match between vaccine and circulating viruses, and the study endpoint chosen.
Fewer influenza vaccine clinical trials have been conducted in the elderly, and available data indicate that vaccine effectiveness is likely lower in this group than among healthy adults. More effective vaccines for elderly populations are clearly needed, and it is encouraging that research is ongoing (5). However, the high rates of influenza-associated hospitalizations and mortality in adults and elderly populations justifies the use of influenza vaccines (even if only moderately effective) to reduce this large burden of disease (10, 11).
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2. Jefferson T, Di Pietrantonj C, Rivetti A, Bawazeer GA, Al-Ansary LA, Ferroni E. Vaccines for preventing influenza in healthy adults. The Cochrane database of systematic reviews. 2014;3:CD001269.
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10. Zhou H, Thompson WW, Viboud CG, Ringholz CM, Cheng P-Y, Steiner C, et al. Hospitalizations Associated With Influenza and Respiratory Syncytial Virus in the United States, 1993–2008. Clinical Infectious Diseases. 2012;54(10):1427-36.
11. Centers for Disease Control and Prevention. Estimates of deaths associated with seasonal influenza --- United States, 1976-2007. MMWR Morbidity and mortality weekly report. 2010;59(33):1057-62.
Competing interests: No competing interests