By Jon Cohen
ScienceNOW Daily News
28 April 2009
The U.S. Centers for Disease Control and Prevention strongly doubts that this year's flu vaccine will offer people any protection from the swine flu. "We don't think that any of the existing vaccines are effective," acting CDC Director Richard Besser said yesterday at a press conference.
But some flu vaccine researchers and public health experts say the jury is still out. "If I hadn't already had the vaccine, I'd take it," says Robert Webster, a flu guru and vaccinemaker at St. Jude Children's Research Hospital in Memphis, Tennessee.
CDC's Daniel Jernigan says experiments with ferrets done there suggest that the current vaccine has no power against the H1N1 strain of swine flu now circulating the globe. CDC researchers took ferrets never infected with an influenza virus and injected them with this year's vaccine, which has an H1N1 component of human, not swine, origin. They then tested the ferrets' blood sera, the part that contains antibodies triggered by the vaccine, against the swine H1N1 from the outbreak. "The sera do not provide any protection," says Jernigan.
CDC 的Daniel Jernigan说在雪貂身上的试验提示当前的（流感）疫苗对于正在全球蔓延的猪流感病毒H1N1亚型没有作用。CDC的研究者把今年含有人类（而非 猪）H1N1亚型成份的疫苗注射到从未感染过流感的雪貂体内，然后检验雪貂的血清——就是疫苗诱发的抗体——看对今年爆发的猪流感H1N1亚型有无作用。 “（结果）血清没有任何预防作用”，Jernigan说。
Then again, as Jernigan acknowledges, antibodies provide only one type of immunity triggered by the vaccine.
The vaccine can also stimulate the cell-mediated arm of the immune system, the part that clears infected cells from the blood. The ferret model did not further test the possibility that vaccination leads to milder disease. And many elderly people may also have some immunity from previous infections with similar influenza viruses or previous vaccinations. "There's a lot of information that we don't have," says Jernigan.
该疫苗能刺激免疫系统的细胞“卫兵”，从而将血液中被（病毒）感染的 细胞清除出去。雪貂模型没有进一步测试疫苗对于更轻微的（流感）疾病的有效性。但是很多年长的人可能通过以前的疫苗免疫，或是感染过类似的流感病毒而获得 某些免疫能力。“还有很多信息我们不清楚”，Jernigan说。（［按］意思是说疫苗可能对轻微症状有作用，并且成年人因某些因素对新的流感病毒会有一 定的免疫力。）
Julio Frenk, dean of Harvard School of Public Health in Boston and the former secretary of health in Mexico, like Webster, suspects that the vaccine may do some good. Frenk notes that Mexico has excellent vaccine coverage of children under 5 years old and the elderly, the two groups that have been spared in this outbreak. "There's a likelihood that there's at least partial protection," says Frenk, who was in Mexico City at the time.
波士顿哈佛大学公共卫生学院的系主任、墨西哥前卫生部长Julio Frenk和Webster持相同的观点，也认为疫苗可能有一定作用。Frenk提到，墨西哥5岁以下及更大一点的孩子都有非常不错的疫苗免疫保护，而这些孩子们在此次爆发的（猪流感）中没有被波及。“疫苗很有可能具有一定的预防作用”，Frenk说。猪流感爆发时，他正在墨西哥城（［按注］墨西哥首 都）。
Webster, who says he wouldn't expect much from the current vaccine because the H1N1 in it differs markedly from the new strain, still says it may make the difference between developing a mild illness and death.