体重超标会削弱流感疫苗的效力

体重超标会削弱流感疫苗的效力

The Centers for Disease Control and Prevention says flu season is starting to ramp up — and it's not too late to reduce your risk with a vaccine.

美国疾病控制与预防中心表示，流感季节正开始升温，现在接种疫苗降低患病风险还为时不晚。

But scientists have come to realize that flu vaccines are less effective for people who are overweight or obese. Considering that excess weight affects more than two-thirds of the U.S. adult population, that's a significant shortcoming.

但科学家们已经意识到，流感疫苗对超重或肥胖的人效果较差。超重影响了超过三分之二的美国成年人，这是一个明显的缺点。

Researchers are studying why that's the case, with an eye toward developing better flu vaccines.

研究人员正在研究为什么会出现这种情况，并着眼于开发更好的流感疫苗。

This issue came to light during the 2009 flu pandemic, the first major outbreak of the 21st century. Health officials noticed that the flu was taking a particular toll on people who were significantly overweight.

这个问题在2009年流感大流行期间被曝光，这是21世纪的第一次大爆发。卫生官员注意到，流感对那些明显超重的人造成了特别严重的影响。

"We had never seen that before," says Schultz-Cherry, an infectious disease specialist at St. Jude Children's Research Hospital.

“我们以前从未见过这种情况，”圣犹大儿童研究医院的传染病专家舒尔茨-切里说。

"The virus is able to grow to higher [concentrations] and spread deeper in your lungs, which is not what you want during an influenza infection," she says.

她说:“这种病毒能够增长到更高的浓度，并传播到肺部更深的地方，这在流感感染期间是不希望发生的。”

And people weren't simply getting sicker — they were also more likely to spread the disease. That has the potential to amplify a flu outbreak.

人们不仅仅是病情加重，他们也更有可能传播疾病。这可能会加剧流感的爆发。

Schultz-Cherry says this point is highlighted in a study of volunteers at the University of Maryland.

舒尔茨-切里说，这一点在马里兰大学对志愿者的研究中得到了强调。

"The students who were overweight/obese actually had more virus coming out in their exhaled breath," Schultz-Cherry says.

舒尔茨-切里说:“实际上，超重或肥胖的学生呼出的病毒更多。”

Another research team studied families in Nicaragua during flu season and found that overweight people shed the virus by an extra day, on average, compared with people of lower body weight. That effect was bigger for people who had no or few symptoms.

另一个研究小组在流感季节研究了尼加拉瓜的家庭，发现超重的人比体重较轻的人平均多一天摆脱病毒。对于没有或很少出现症状的人，这种影响更大。

"What's particularly disturbing for us is the fact that the vaccine doesn't work as well" in this population, says Melinda Beck, a professor of nutrition at the University of North Carolina at Chapel Hill. She's been studying the effect of obesity on a person's ability to fend off infections.

北卡罗来纳大学教堂山分校的营养学教授梅琳达·贝克说，“对我们来说，尤其令人不安的是，疫苗在这一人群中的效果并不好”。她一直在研究肥胖对一个人抵御感染能力的影响。

She looked at the two different parts of the immune system: one involves antibodies, which are proteins that can neutralize viruses; the other involves cells that join in on the fight against disease.

她研究了免疫系统的两个不同部分:一个是抗体，这是一种可以中和病毒的蛋白质;另一种是参与对抗疾病的细胞。

"You usually think of the vaccine as protecting you with antibodies," she says. "And in fact, obese people could make a nice antibody response." The part of the immune system that fails in this case involves the T cells, she says.

“你通常认为疫苗是用抗体保护你，”她说。“事实上，肥胖的人可以产生很好的抗体反应。”她说，在这种情况下，免疫系统失败的部分与T细胞有关。

As people become overweight, their metabolism changes. And Beck says that metabolic shift affects many cells, including immune system cells. She has studied the details of this in mice.

当人们超重时，他们的新陈代谢就会改变。贝克说，新陈代谢的改变会影响许多细胞，包括免疫系统细胞。她在老鼠身上研究了这些细节。

Elderly people face the same problem. "Sometimes they can make an antibody response, but it's their T cells that aren't functioning, so they can still get infected with flu even though they've been vaccinated," she says.

老年人也面临着同样的问题。她说:“有时他们会产生抗体反应，但这是他们的T细胞不起作用，所以即使他们接种了疫苗，他们仍然会感染流感。”

As a result, a "30-year-old obese person has the immune cells that look a lot like what you might expect in an 80-year-old individual," Beck says.

结果，“一个30岁的肥胖者的免疫细胞看起来很像一个80岁的人，”贝克说。

That may be why flu vaccines don't work so well in older people, either. So it's possible that improvements in the vaccine will help both people who are older as well as those who are overweight.

这也许就是为什么流感疫苗在老年人身上效果不佳的原因。因此，疫苗的改进有可能对老年人和超重人群都有帮助。

Schultz-Cherry is part of a new effort at the National Institutes of Health to come up with a next-generation flu vaccine.

舒尔茨-切里是美国国立卫生研究院开发新一代流感疫苗的新努力的一部分。

"That's exactly our hope — that we can find a vaccine that will work for everybody, but especially for these higher-risk populations," she says.

她说:“这正是我们的希望——我们能够找到一种对所有人都有效的疫苗，尤其是对高危人群。”

That effort will take many years. In the meantime, Schultz-Cherry says it's still important for everyone to get vaccinated.

这一努力将需要多年时间。与此同时，舒尔茨-切里说，对每个人来说，接种疫苗仍然很重要。