體重超標會削弱流感疫苗的效力

體重超標會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.

美國疾病控制與預防中心表示，流感季節(jié)正開始升溫，現(xiàn)在接種疫苗降低患病風險還為時不晚。

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.

但科學家們已經(jīng)意識到，流感疫苗對超重或肥胖的人效果較差。超重影響了超過三分之二的美國成年人，這是一個明顯的缺點。

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

研究人員正在研究為什么會出現(xiàn)這種情況，并著眼于開發(fā)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.

這個問題在2009年流感大流行期間被曝光，這是21世紀的第一次大爆發(fā)。衛(wèi)生官員注意到，流感對那些明顯超重的人造成了特別嚴重的影響。

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

“我們以前從未見過這種情況，”圣猶大兒童研究醫(yī)院的傳染病專家舒爾茨-切里說。

"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.

她說:“這種病毒能夠增長到更高的濃度，并傳播到肺部更深的地方，這在流感感染期間是不希望發(fā)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.

人們不僅僅是病情加重，他們也更有可能傳播疾病。這可能會加劇流感的爆發(fā)。

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

舒爾茨-切里說，這一點在馬里蘭大學對志愿者的研究中得到了強調(diào)。

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

舒爾茨-切里說:“實際上，超重或肥胖的學生呼出的病毒更多。”

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.

另一個研究小組在流感季節(jié)研究了尼加拉瓜的家庭，發(fā)現(xiàn)超重的人比體重較輕的人平均多一天擺脫病毒。對于沒有或很少出現(xiàn)癥狀的人，這種影響更大。

"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.

北卡羅來納大學教堂山分校的營養(yǎng)學教授梅琳達·貝克說，“對我們來說，尤其令人不安的是，疫苗在這一人群中的效果并不好”。她一直在研究肥胖對一個人抵御感染能力的影響。

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.

她研究了免疫系統(tǒng)的兩個不同部分:一個是抗體，這是一種可以中和病毒的蛋白質(zhì);另一種是參與對抗疾病的細胞。

"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.

“你通常認為疫苗是用抗體保護你，”她說。“事實上，肥胖的人可以產(chǎn)生很好的抗體反應。”她說，在這種情況下，免疫系統(tǒng)失敗的部分與T細胞有關(guān)。

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.

當人們超重時，他們的新陳代謝就會改變。貝克說，新陳代謝的改變會影響許多細胞，包括免疫系統(tǒng)細胞。她在老鼠身上研究了這些細節(jié)。

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.

老年人也面臨著同樣的問題。她說:“有時他們會產(chǎn)生抗體反應，但這是他們的T細胞不起作用，所以即使他們接種了疫苗，他們?nèi)匀粫腥玖鞲小?rdquo;

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.

結(jié)果，“一個30歲的肥胖者的免疫細胞看起來很像一個80歲的人，”貝克說。

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.

這也許就是為什么流感疫苗在老年人身上效果不佳的原因。因此，疫苗的改進有可能對老年人和超重人群都有幫助。

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

舒爾茨-切里是美國國立衛(wèi)生研究院開發(fā)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.

她說:“這正是我們的希望——我們能夠找到一種對所有人都有效的疫苗，尤其是對高危人群。”

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

這一努力將需要多年時間。與此同時，舒爾茨-切里說，對每個人來說，接種疫苗仍然很重要。