新证据表明汞和孤独症之间不存在关联性
初为父母的人可能不确定该不该给孩子接种疫苗。很多儿科医生和美国儿科协会会告诉这些父母，疫苗接种不仅安全而且对孩子健康十分重要。不过，在Google里搜索“疫苗安全”后你可能会得到大量的相互冲突的信息。对爱子心切但缺乏专业医学知识的父母而言，从这些信息里辨别真伪无异于大海捞针。名人如詹尼·麦肯锡一直在声称MMR疫苗是她儿子患孤独症的罪魁祸首。此外，颇具争议性的人物如安德鲁·维克菲尔德博士，他首先提出疫苗可能导致孤独症，但后来却遭受质疑并深陷泥沼。1
Now a new study debunks one of the major myths surrounding vaccines: that the preservative thimerosal, which contains a form of mercury called ethylmercury, causes autism. A new study, which will be published in the October issue of Pediatrics, followed more than 1,000 children, comparing mercury exposure with rates of autism, and found no correlation. 18 other epidemiological studies have also investigated the possible connection between autism and vaccines, and found no link.
现在一项新的研究揭开了有关疫苗的传言：广泛用于疫苗防腐剂的硫柳汞含有氯化乙基汞，能导致孤独症。这项新研究将刊登在十月份的“儿科”期刊上。该研究通过对1000多名儿童汞接触量与患孤独症率进行对比，并未发现二者有任何相关性。另外18项流行病研究也对孤独症和疫苗之间可能的关系进行了调查，同样未发现任何结果。1
As a precaution, manufacturers have worked over the last ten years to remove thimerosal from most vaccines (or reduce it to trace amounts), with the exception of the flu vaccine, which is available without the preservative upon request. It’s important to note, however, that while methylmercury found in some types of fish can build up in the body and harm the developing brain of a growing child, the ethylmercury in thimerosal does not build up in the body.
事实上，在过去的十年间，生产厂家为了预防可能发生的情况一直努力把硫柳汞从大部分疫苗中去掉（或减少至痕量），唯一的例外是流感疫苗，因为根据规定，流感疫苗并未加入任何防腐剂。所以，父母们应该懂得，虽然之前有发现甲基汞在某些鱼类体内堆积损害儿童大脑发育的案例，但是硫柳汞里的氯化乙基汞不会。1
Vaccines are not 100% effective on their own; on average about 95 percent of the protection comes from the shot, but the remaining 5 percent comes from living in a community where there are low disease rates. So for vaccines to work, immunization rates must be high so the few people that unable to be vaccinated –- infants or children with compromised immune systems -- will be protected by what’s called “herd” immunity. When vaccine rates drop, deadly diseases can re-emerge – as we’ve seen recently with the whooping cough epidemic in California. Still, fears about the safety of vaccines persist.
疫苗并非百分百具有免疫效力，平均95%的保护来自疫苗接种，剩余5%的保护依靠接种者所在的低发病率环境。所以，为确保疫苗的作用，一个地区要达到相对高的疫苗接种率，以便不适合接种疫苗的人群，如免疫力低下的婴儿和儿童，能够受到群体免疫力的保护。接种率一旦下降，致命的疾病就有可能“卷土重来”，最近在加州大规模爆发的百日咳疫情就是一例。当然，对其疫苗安全的担忧仍然存在。1
