FLU NEWS SCAN: Human flu in pigs, H1N1 vaccine response in dialysis patients

May 30, 2012

Study: Antibodies to human flu viruses common in Cambodian pigs
A serologic study of Cambodian pigs found for the first time that exposure to human influenza A is relatively common in the country's swine, researchers reported yesterday in Influenza and Other Respiratory Viruses. The group from Cambodia's Pasteur Institute based its findings on an analysis of 1,147 blood samples obtained from pigs going through a slaughterhouse in Phnom Penh from 2006 to 2010. They noted that most Cambodian swine are raised on small farms in proximity to humans and other animal species. So far, swine influenza viruses have never been isolated in Cambodia, and only rarely in surrounding countries. Antibodies against influenza A were detected in 14.9% of samples. The 2009 pandemic H1N1 virus was found after the pandemic virus reached Cambodia and was the most frequently found virus, peaking in 2010, followed by seasonal H1N1 and H3N2 subtypes, which peaked in 2008. Researchers found that some of the pigs had been exposed to more than one human flu virus, a factor they said could lead to reassortment events that could produce new pathogenic variants. Tests on 150 random samples found no evidence of H5N1 avian influenza exposure. The investigators concluded that more systematic surveillance systems are needed to monitor influenza A viruses on farms rather than just slaughterhouses.
 May 29 Influenza Other Respi Viruses abstract

Without adjuvant, H1N1 vaccine induces weak response in dialysis patients
A study from Taiwan suggests that a single dose of 2009 H1N1 influenza vaccine without an adjuvant induces only a weak immune response in adult and elderly hemodialysis patients, according to a report today in Vaccine. The researchers administered the monovalent vaccine to 110 hemodialysis patients and 173 healthy volunteers. Only 25.4% of adult (ages 18 to 60) and 23.4% of elderly (over 60) dialysis patients showed seroconversion (at least a fourfold increase in hemagglutination-inhibition antibody titer) after vaccination. Similarly, both groups showed only a 1.8-fold increase in geometric mean titer after vaccination. Immune responses were significantly higher in the healthy volunteers. When participants who had elevated antibodies before vaccination (a titer of 1:40 or higher) were excluded from the analysis, the results were similar. The researchers also found that cholesterol and hemoglobin levels were significant predictors of the immune response in dialysis patients, suggesting that nutrition status and anemia played a role. The report says previous studies showed that adjuvanted H1N1 vaccines generated varying responses in dialysis patients.
May 30 Vaccine abstract

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