Argumenty przeciwko masowym i uniwersalnym szczepieniom przeciwgrypowym

Mar 1, 2013 (CIDRAP News) – Experts are puzzled by a new study in which influenza vaccination seemed to provide little or no protection against flu in the 2010-11 season—and in which the only participants who seemed to benefit from the vaccine were those who hadn’t been vaccinated the season before.

The investigators recruited 328 households in Michigan before the flu season started and followed them through the season. Overall, they found that the infection risk was nearly the same in vaccinated and unvaccinated participants, indicating no significant vaccine-induced protection, according to their report in Clinical Infectious Diseases. That contrasted sharply with several other observational studies that found the vaccine to yield about 60% protection during the same season. In trying to figure out why the effectiveness was so low, the researchers sifted their data in different ways, said Arnold S. Monto, MD, of the University of Michigan, senior author of the study. „We discovered that if you separated out those that had not been vaccinated the previous year, you got percentages close to what were seen in the major vaccine effectiveness studies,” he told CIDRAP News.

„We were playing with this for a long time, and there was clear interaction of sequential vaccination and vaccine effectiveness, looking at it in a strictly statistical way,” he added. „We felt it had to be separated out.” The vaccine was found to be 62% effective in those who hadn’t been vaccinated the previous year. That was similar to findings in the other observational studies and also to the results of a recent, rigorous meta-analysis of randomized controlled trials. In contrast, those who had been vaccinated 2 years in a row (before both the 2009-10 and 2010-11 seasons) got no significant protection.

The findings come amid a growing number of studies that raise questions about flu vaccine effectiveness (VE). They include, among others, last week’s CDC report that this year’s vaccine has worked poorly in elderly people and three recent European studies showing that vaccine-induced immunity in the 2011-12 season waned after 3 to 4 months. Other studies have cast doubt on the long-standing belief that a close match between the vaccine virus strains and circulating strains improves VE.

„If we don’t go back and revisit our current vaccine recommendations, I think we stand to lose a great deal of credibility with both the medical community and even the general public as to the trustworthiness of what public health concludes and promotes,” he said. „This is exactly why we need game-changing influenza vaccines.”

„An increased risk of H1N1 related admission to hospital was observed during the first 1-7 days after receiving the pandemic vaccine, with vaccine effectiveness estimates of −258% (95% confidence interval −464% to −127%) compared with those who did not receive either the pandemic or the seasonal vaccines. No significant effectiveness of the pandemic vaccine was observed 8-14 days after vaccination and the analysis indicated a non-significant protective effect, with 44% (95% confidence interval −19% to 73%) vaccine effectiveness 14 days or more after receiving the pandemic vaccine (table 2). Those who received only the 2009-10 seasonal influenza vaccine had an increased risk of H1N1 related hospital admission (hazard ratio 2.55, 95% confidence interval 1.38 to 4.70; table 2).”

„… In the present study, we compared influenza A virus-specific cellular and humoral responses of unvaccinated healthy control children with those of children with cystic fibrosis (CF) who were vaccinated annually. Similar virus-specific CD4(+) T cell and antibody responses were observed, while an age-dependent increase of the virus-specific CD8(+) T cell response that was absent in vaccinated CF children was observed in unvaccinated healthy control children. Our results indicate that annual influenza vaccination is effective against seasonal influenza but hampers the development of virus-specific CD8(+) T cell responses. The consequences of these findings are discussed in the light of the development of protective immunity to seasonal and future pandemic influenza viruses.”

„CONCLUSION: A significant positive association between the seasonal influenza vaccine and lab confirmed pH1N1 was observed after considering multiple confounders and using different methods for confounder adjustment. This was not likely explained by an unmeasured confounder given the prevalence and strength of association needed to result in a non-significant association.”

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