辉瑞疫苗对南非变种到底是不够有效，还是放大了危害？
以色列研究：南非变种病毒可突破辉瑞疫苗文 / 林煇智发布 / 2021年4月11日 9:23 PM
（早报讯）以色列研究机构研究显示，南非发现的变种病毒在一定程度上能“突破”辉瑞疫苗的防护网。不过该研究尚未经过同行评审。
路透社报道，特拉维夫大学及以色列医疗服务机构克拉利特研究所周六（10日）公布的最新研究，团队将800名冠病患者分成两批，一批是没有接种疫苗的确诊者，另一批则是接种了一剂或两剂辉瑞疫苗14天后仍感染的确诊者。
研究发现，研究对象中1％感染的是南非发现的变种病毒，其中，接种了两剂辉瑞疫苗后仍确诊的患者，感染该变种病毒的机率是未接种疫苗者的近八倍，感染率分别为5.4％和0.7％。
特拉维夫大学专家斯特恩称，和未接种疫苗的患者相比，接种两剂疫苗的患者感染南非发现的变种病毒的几率更高。这意味该变种病毒在一定程度上能够“突破”辉瑞疫苗的保护作用。
不过研究人员也强调，由于南非发现的变种病毒在以色列的感染率较低，这项研究样本不多，也无法推论出辉瑞疫苗对该变种病毒的整体保护效力。此研究也尚未经过同行评审。辉瑞及德国BioNTech公司尚未对此发表评论。
据报道，辉瑞和BioNTech公司今年4月1日曾表示，他们生产的疫苗在预防冠病病毒上有效率高达91％，并在加入了新的临床数据后声称，疫苗对南非发现的变种病毒有效。
http://www.aswetalk.net/bbs/forum.php?mod=post&action=newthread&fid=167
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South African variant may evade protection from Pfizer vaccine, Israeli study says
By Maayan Lubell
4 MIN READ
JERUSALEM (Reuters) -The coronavirus variant discovered in South Africa may evade the protection provided by Pfizer/BioNTech’s COVID-19 vaccine to some extent, a real-world data study in Israel found, though its prevalence in the country is very low and the research has not been peer reviewed.
The study, released on Saturday, compared almost 400 people who had tested positive for COVID-19, 14 days or more after they received one or two doses of the vaccine, against the same number of unvaccinated patients with the disease.
It matched age and gender, among other characteristics.
The South African variant, B.1.351, was found to make up about 1% of all the COVID-19 cases across all the people studied, according to the study by Tel Aviv University and Israel’s largest healthcare provider, Clalit.
But among patients who had received two doses of the vaccine, the variant’s prevalence rate was eight times higher than those unvaccinated - 5.4% versus 0.7%.
This suggests the vaccine is less effective against the South African variant, compared with the original coronavirus and a variant first identified in Britain that has come to comprise nearly all COVID-19 cases in Israel, the researchers said.
“We found a disproportionately higher rate of the South African variant among people vaccinated with a second dose, compared to the unvaccinated group. This means that the South African variant is able, to some extent, to break through the vaccine’s protection,” said Tel Aviv University’s Adi Stern.
The researchers cautioned, though, that the study only had a small sample size of people infected with the South African variant because of its rarity in Israel.
They also said the research was not intended to deduce overall vaccine effectiveness against any variant, since it only looked at people who had already tested positive for COVID-19, not at overall infection rates.
Pfizer declined to comment on the Israeli study.
Pfizer and BioNTech said on April 1 that their vaccine was around 91% effective at preventing COVID-19, citing updated trial data that included participants inoculated for up to six months.
Training nurse Sari Roos prepares a dose of Pfizer/BioNTech vaccine against coronavirus disease (COVID-19) to teach her air bubble technique in Laakso hospital in Helsinki, Finland March 11, 2021. Picture taken March 11, 2021. REUTERS/Essi Lehto
They have been testing a third dose of their shot as a booster, and have said they could modify the shot to specifically address new variants if needed.
In respect to the South African variant, they said that among a group of 800 study volunteers in South Africa, where B.1.351 is widespread, there were nine cases of COVID-19, all of which occurred among participants who got the placebo. Of those nine cases, six were among individuals infected with the South African variant.
Some previous studies have indicated that the Pfizer/BioNTech shot was less potent against the B.1.351 variant than against other variants of the coronavirus, but still offered a robust defence.
VARIANT IS NOT WIDESPREAD
While the results of the study may cause concern, the low prevalence of the South African strain was encouraging, according to Tel Aviv University’s Stern.
“Even if the South African variant does break through the vaccine’s protection, it has not spread widely through the population,” said Stern, adding that the British variant may be “blocking” the spread of the South African strain.
Almost 53% of Israel’s 9.3 million population has received both Pfizer doses. Israel has largely reopened its economy in recent weeks while the pandemic appears to be receding, with infection rates, severe illness and hospitalizations dropping sharply.
About a third of Israelis are below the age of 16, which means they are still not eligible for the shot.
Reporting by Maayan LubellEditing by Pravin Char and Frances Kerry
https://www.reuters.com/article/uk-health-coronavirus-israel-study-idUSKBN2BX0JX
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上面是新加坡《联合早报》的报导，下面是路透社的报导。“突破”是break through的直译。
疑问在于：
研究发现，研究对象中1％感染的是南非发现的变种病毒，其中，接种了两剂辉瑞疫苗后仍确诊的患者，感染该变种病毒的机率是未接种疫苗者的近八倍，感染率分别为5.4％和0.7％。
这应该怎么解读？
0.7%应该是人口中感染南非病毒的比率。400人的样本小了点，但还是有点意义。
要是辉瑞只是对南非变种不管用，那是一回事；要是接种之后反而容易受到南非变种的感染，那就是另一回事了。
AZ已经翻车了，辉瑞也要翻车？ 还得刨除打了疫苗的四处浪还不防护 The percentage doesn't make sense.Do the math. holycow 发表于 2021-4-11 14:33
The percentage doesn't make sense.Do the math.
我反正看不懂。你的结论是什么？ 本帖最后由 holycow 于 2021-4-11 14:16 编辑
晨枫 发表于 2021-4-11 13:28
我反正看不懂。你的结论是什么？
The South African variant, B.1.351, was found to make up about 1% of all the COVID-19 cases across all the people studied, according to the study by Tel Aviv University and Israel’s largest healthcare provider, Clalit.
800 * 1% = 8
But among patients who had received two doses of the vaccine, the variant’s prevalence rate was eight times higher than those unvaccinated - 5.4% versus 0.7%.
400 * 5.4% = 22
400 * 0.7% = 3
22 + 3 = 25
再退一步说，就算那些数字都对得上，打过疫苗仍然得病的人群中变种病毒的prevailing rate比例更高，几乎可以说是foregone conclusion, 从进化和自然选择的角度就可以推出来。假设打过两针疫苗以后对原版病毒的保护率是90%, 对南非变种的保护率是60%, 在已经中招的这个给定前提条件下，必然会出现南非变种的prevailing rate超出对照组的情况(对照组对两种病毒的保护率是一样的，都是0)。所以这样设计的实验，其结果不能说明任何问题。 holycow 发表于 2021-4-11 16:51
800 * 1% = 8
@晨枫
我的理解是原文没有给出两组各自的总感染率，而是说在打针组病例中变种占5.4%， 而没打组变种占0.7%，
但原文最后还是说打针有很好的保护力，所以疫苗有保护力，但对变种的保护力没有那么强，所以有感染，但总的感染率应该低于没打的。
holycow 发表于 2021-4-11 16:51
800 * 1% = 8
@晨枫
而且文章标题有误导 -South African variant may evade protection from Pfizer vaccine
本来就不是100%，而是95%， 也就是本来evade就存在，变种拉低了这个95%，但没有那么差。 sylvia 发表于 2021-4-11 14:50
@晨枫
我的理解是原文没有给出两组各自的总感染率，而是说在打针组病例中变种占5.4%， 而没打组变种占0. ...
两组各自的总感染率都是100%，每个人都是中过招的。
The study, released on Saturday, compared almost 400 people who had tested positive for COVID-19, 14 days or more after they received one or two doses of the vaccine, against the same number of unvaccinated patients with the disease. 翻车点可能不同，是在于辉瑞疫苗可能暗含某种指定病毒的特殊通道，刚好被南非变异周走通了 小书童 发表于 2021-4-11 20:51
翻车点可能不同，是在于辉瑞疫苗可能暗含某种指定病毒的特殊通道，刚好被南非变异周走通了 ...
就怕这个，要是真这样，这祸就闯大了 也许是因为疫苗对未变异株更加有效，从而使突变株获得了相对的竞争优势。未必是疫苗“帮助”了突变株。 zhuyi2005 发表于 2021-4-11 21:22
也许是因为疫苗对未变异株更加有效，从而使突变株获得了相对的竞争优势。未必是疫苗“帮助”了突变株。 ...
不管怎么说，这个研究的结论会很有意思，打破了很多预想 800人感染，1%是南非变种，就是8个人。其中大概3个属于打过疫苗的55人组；5个人属于没打疫苗的745人组。。。咔咔 独角兽 发表于 2021-4-11 22:12
800人感染，1%是南非变种，就是8个人。其中大概3个属于打过疫苗的55人组；5个人属于没打疫苗的745人组。。 ...
这个55人组和745人组是怎么算出来的？ holycow 发表于 2021-4-11 15:51
800 * 1% = 8
我再看了一遍原文，还是看不懂是怎么算出来的。我明白你的意思，但看不懂原文的算法。还是让子弹飞一会儿吧 晨枫 发表于 2021-4-12 12:29
这个55人组和745人组是怎么算出来的？
根据这不靠谱的文章猜出来的。1~7，2～6，3～5。分别除以各自百分比。加起来是800的就差不多猜对了。 独角兽 发表于 2021-4-11 22:39
根据这不靠谱的文章猜出来的。1~7，2～6，3～5。分别除以各自百分比。加起来是800的就差不多猜对了。 ...
这是凑数的算法，但文章里确实说到400人是接种过疫苗的啊。所以这些数字碰不起来，叫人抓狂。莫不是被文科生耍了吧？还是我们的统计都退化到这个地步了？ 晨枫 发表于 2021-4-12 12:44
这是凑数的算法，但文章里确实说到400人是接种过疫苗的啊。所以这些数字碰不起来，叫人抓狂。莫不是被文 ...
我刚刚没点开原文看，或者那个链接是实验本身文章还是一个不怎么靠谱的解读。因为总数800人，1%是8个人南非变种。就是神牛算的。如果打疫苗没打疫苗都是400人，那么按各自比例算出来的总变种人数是25，而不是8个，对不上。
而我做猜测比较符合可能的实际情况。800个感染者，其中打过疫苗的比较少，所以疫苗有保护作用 并且相当显著。但因为对变种的保护比没变种的低，所以，打疫苗组变种的比例高。如果8个数据的统计学意义可以相信的话。 独角兽 发表于 2021-4-11 22:58
我刚刚没点开原文看，或者那个链接是实验本身文章还是一个不怎么靠谱的解读。因为总数800人，1%是8个人南 ...
所以说看不懂这是怎么算出来的。越来越怀疑是被文科生耍了。{:204:} 接受疫苗后的患者中，因为疫苗对其他变种抵抗性更高，于是就显得感染南非变种的几率比一般人群高。但实际两组的几率还要再乘以普通人群感染新冠的几率和接受疫苗人群感染新冠的几率。如果pfizer号称的91%有效性是真实的话，打了疫苗以后感染南非变种的几率还是要比普通人群低一些，只是没有那么强的有效性，这也是为什么他们还要再研发针对南非变种的booster
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