完整标题：BBC：牛津疫苗防护力达7成
发稿单位：中央社
发稿时间：2020/11/23 16:00
撰 稿 者：杨昭彦
原文连结：https://www.cna.com.tw/news/aopl/202011230168.aspx
一项大规模试验结果显示，英国牛津大学（University of Oxford）研发的2019冠状病毒
疾病（COVID-19，武汉肺炎）疫苗，可防止7成受试者出现症状。
之前美国辉瑞大药厂（Pfizer）与莫德纳生物技术公司（Moderna）已分别表示，旗下疫
苗试验结果显示防护力达95%。牛津大学试验结果虽堪称成功，却也令人失望。
然而英国广播公司（BBC）报导，相较于另外两种疫苗，牛津大学疫苗价格便宜得多，而
且储存更容易，更方便送到全球各个角落。
英国政府已预订1亿剂牛津大学疫苗，足够替5000万人接种。
参与牛津大学疫苗试验的志愿者超过2万人，其中一半在英国进行，其余在巴西受试。研
究者说疫苗防护力为70%。
有趣的是，有一群志愿者先接种半剂疫苗后，再接受完整的一剂疫苗，防护效力就增至9
成。目前还不清楚为何有此差异。
Covid-19: Oxford University vaccine shows 70% protection
https://www.bbc.com/news/health-55040635
There were 30 cases of Covid in people who had two doses of the vaccine and
101 cases in people who received a dummy injection.
The researchers said it works out at 70% protection.
When volunteers were given two "high" doses the protection was 62%, but this
rose to 90% when people were given a "low" dose followed by a high one. It's
not clear why there is a difference.
Why is the low dose better?
There is not a straightforward answer.
One idea is the immune system rejects the vaccine, which is built around a
common cold virus, if it is given in too big an initial dose.
Or a low then high shot may be a better mimic of a coronavirus infection and
lead to a better immune response.
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中央社要翻BBC新闻也不完整翻,BBC有提到很多资讯,包括差异可能的原因,还有价格等
苹果有采访到李秉颖医师说明为什么第1剂减量会较有效
因产生的抗体会杀掉第2剂的活病毒
牛津疫苗保护力7成不够强? 专家剖析先天劣势和优势(2020-11-23)
https://tw.appledaily.com/life/20201123/GW6F2II3JREVLBVFUV3I7D42MQ/