Vaccines create more powerful strains of bacteria and viruses. "Vaccination against 2 avian viruses, the Marek disease virus, and the infectious bursal disease virus, were associated with the emergence of more virulent strains . ...Based on mathematical modeling, vaccines designed to reduce pathogen growth rate and/or toxicity may result in the evolution of pathogens with higher levels of virulence (36)." wwwnc.cdc.gov/eid/article/15/8/08-1511_article.htm "Hib immunization contributed to an increased risk for H. influenzae type a meningitis through selection of circulating H. influenzae type a clones." " the incidence for H. influenzae type a meningitis increased 8-fold" jid.oxfordjournals.org/content/187/1/109.full.pdf+html "Together, our data suggest that the high level of vaccine failure in Nicaraguan is probably not due to antigenic drift of commonly circulating virus strains nor the emergence of new antigenetically distinct virus strains. Furthermore, our data suggest that the widespread use of the RotaTeq vaccine has led to the introduction of vaccine genes into circulating human RotaViruses" Infect Genet Evol. 2012 Aug;12 ncbi.nlm.nih.gov/pubmed/22487061
Posted on: Thu, 05 Sep 2013 00:09:21 +0000
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