肥胖会影响流感疫苗的反应


  【24drs.com】根据在线国际肥胖期刊(International Journal of Obesity)上的一篇研究结论,随著流感季节开始,北卡罗来纳大学教堂山分校的研究者首次提出,流感疫苗对肥胖者的保护力可能小于健康体重者。
  
  一项针对学院门诊中心接种疫苗患者所进行的研究,前两年的结果指出,身体质量指数(BMI)较高与接种疫苗后12个月流感抗体降低较多有关;之前的研究认为肥胖与感染流感风险有关,但是这是首度有研究者检测接种疫苗后的抗体。
  
  北卡罗来纳大学教堂山分校Gillings全球公卫学院营养系的Patricia Sheridan博士等人藉由接种疫苗后的血清检测发现,对三价流感疫苗而言,体重对于刚接种后反应的影响不大,不过,12个月后检测CD8+ T细胞反应时发现,肥胖程度提高时,流感抗体降低达4倍,CD8+ T细胞不足以预防感染流感,但还是有助于减轻严重性和加速病毒清除。
  
  北卡罗来纳大学教堂山分校Gillings全球公卫学院营养系副主任Melinda Beck教授在声明中表示,这些结果认为,过重和肥胖者比健康体重者更可能被流感病毒感染,这些新结果似乎让我们有理由了解为何在H1N1大流行时,肥胖者比健康体重者更容易发病。
  
  研究人员在2009年流感季检测了461名18岁以上的成人病患、在2010年检测了74人;这些病患29.7%是健康体重(BMI,18.5 - 24.9 kg/m2)、33.4%是过重(BMI,25 - 29.9 kg/m2)、35.5%是肥胖(BMI,≧30 kg/m2),其它1.4%体重过轻。
  
  接种疫苗12个月后,50%的肥胖病患显示对两种流感病毒株的抗体效价降低至少4倍,相较之下,健康体重者不到25%出现这种程度的抗体效价降低。
  
  肥胖也会降低成人对B型肝炎疫苗、孩童对破伤风疫苗的抗体反应。
  
  根据世界卫生组织统计,全球的肥胖人口超过10%,美国人口超过三分之一是过重或肥胖。
  
  资料来源:http://www.24drs.com/professional/list/content.asp?x_logon=W&x_idno=6638&x_classno=0
  

Obesity Affects Influenza Vaccine Response

By Larry Hand
Medscape Medical News

October 25, 2011 — As the influenza season opens this month, researchers at the University of North Carolina at Chapel Hill warn for the first time that obese individuals may be getting less protection from vaccines than healthy-weight people. They reported their conclusions in an article published online October 25 in the International Journal of Obesity.

In an ongoing study involving patients getting vaccinated at an academic outpatient center, results from the first 2 years indicate that higher body mass index (BMI) is associated with a larger drop in influenza antibodies 12 months after vaccination with trivalent influenza vaccine. Previous research had linked obesity to risk for influenza infection, but this is the first time researchers have tested for antibodies a year after vaccination.

Using serum tests just after vaccination, Patricia Sheridan, PhD, from the Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, and colleagues found that weight did not make a significant difference in the initial response to trivalent influenza vaccine. However, in testing for CD8+ T-cell responses to vaccines 12 months later, the researchers discovered that as obesity levels increased, influenza antibodies decreased up to 4-fold. The CD8+ T-cells do not prevent infection by influenza, but they do help decrease severity and speed up viral clearance.

"These results suggest that overweight and obese people would be more likely than healthy weight people to experience flu illness following exposure to the flu virus," Melinda Beck, PhD, professor and associate chair of nutrition at the University of North Carolina Gillings School of Global Public Health and senior author, said in a statement. "These new findings seem to give us a reason why obese people were more susceptible to influenza illness during the H1N1 pandemic compared to healthy weight people."

Researchers tested 461 adult patients aged 18 years or older during the 2009 influenza season, as well as 74 patients for the 2010 season. Of all the participants, 29.7% were healthy-weight individuals (BMI, 18.5 - 24.9 kg/m2), 33.4% were overweight (BMI, 25 - 29.9 kg/m2), and 35.5% were obese (BMI, ?30 kg/m2). The remaining 1.4% were underweight.

Twelve months after vaccination, 50% of the obese patients showed at least a 4-fold decrease in antibody titers to 2 influenza strains. In comparison, less than 25% of the healthy-weight patients experienced similar large decreases in antibody titers.

Obesity also has been shown to reduce antibody response to hepatitis B vaccine in adults, and tetanus vaccine in children.

According to the World Health Organization, more than 10% of the world population is obese, and more than two thirds of the US population is overweight or obese.

Int J Obes. Published online October 25, 2011.

    
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