为何接种疫苗后仍会感染？如何理解疫苗有效率

华尔街见闻2021-07-29

随着变种病毒肆虐，新冠疫情在全球呈现复燃之势。更让人感到不安的是，有不少确诊病例是已经接种过疫苗的人群。例如，美国华裔体操运动员卡拉·埃克(Kara Eaker)和英国卫生大臣赛义德·贾维德(Sajid Javid)都是在接种疫苗后，被检测出新冠阳性，均被诊断为“突破性感染”(Breakthrough Infection)。那么到底什么是突破性感染？为何接种疫苗后仍会感染？这种现象有多普遍，又...

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}\n.meta {color:#5e5c6d;font-size:13px;margin:0 0 .5em; }\na{text-decoration:none; color:#2a4b87;}\n.meta .head { display: inline-block; overflow: hidden}\n.head .h-thumb { width: 30px; height: 30px; margin: 0; padding: 0; border-radius: 50%; float: left;}\n.head .h-content { margin: 0; padding: 0 0 0 9px; float: left;}\n.head .h-name {font-size: 13px; color: #eee; margin: 0;}\n.head .h-time {font-size: 11px; color: #7E829C; margin: 0;line-height: 11px;}\n.small {font-size: 12.5px; display: inline-block; transform: scale(0.9); -webkit-transform: scale(0.9); transform-origin: left; -webkit-transform-origin: left;}\n.smaller {font-size: 12.5px; display: inline-block; transform: scale(0.8); -webkit-transform: scale(0.8); transform-origin: left; -webkit-transform-origin: left;}\n.bt-text {font-size: 12px;margin: 1.5em 0 0 0}\n.bt-text p {margin: 0}\n</style>\n</head>\n<body>\n<div class=\"wrapper\">\n<header>\n<h2 class=\"title\">\n为何接种疫苗后仍会感染？如何理解疫苗有效率\n</h2>\n\n<h4 class=\"meta\">\n\n\n2021-07-29 13:52 北京时间&nbsp;&nbsp;&nbsp;<a href=https://wallstreetcn.com/articles/3636611><strong>华尔街见闻</strong></a>\n\n\n</h4>\n\n</header>\n<article>\n<div>\n<p>随着变种病毒肆虐，新冠疫情在全球呈现复燃之势。更让人感到不安的是，有不少确诊病例是已经接种过疫苗的人群。\n例如，美国华裔体操运动员卡拉·埃克(Kara Eaker)和英国卫生大臣赛义德·贾维德(Sajid Javid)都是在接种疫苗后，被检测出新冠阳性，均被诊断为“突破性感染”(Breakthrough Infection)。\n那么到底什么是突破性感染？为何接种疫苗后仍会感染？这种现象有多普遍，又...</p>\n\n<a href=\"https://wallstreetcn.com/articles/3636611\">Source Link</a>\n\n</div>\n\n\n</article>\n</div>\n</body>\n</html>\n","isBrief":false,"type":0,"news_type":1,"symbol":null,"symbol_name":null,"start_time":0,"source_url":"https://wallstreetcn.com/articles/3636611","article_id":"2155977655","we_media_id":null,"thumbnails":["https://static.tigerbbs.com/6e474d690ea02c536f0fd4c03fc3ddef"],"rights":{"source":"wallstreetcn_api","url":"https://wallstreetcn.com/articles/3636611","rn_cache_url":null,"directOrigin":true},"url":"https://stock-news.laohu8.com/highlight/detail?id=2155977655","pubTimestamp":1627537962,"columns":[],"sourceInfo":{"source_id":"wallstreetcn_api","name":"华尔街见闻"},"weMediaInfo":null,"summary":"95%的疫苗效力并不意味着疫苗能保护95%的人，而其他5%的人会感染病毒。","collect":0,"end_time":0,"defaultTopTitle":"wallstreetcn.com","property":[],"viewcount":null,"language":"zh","relate_stocks":{},"translate_title":"Why are you still infected after vaccination? How to understand the efficacy of vaccines","themeId":null,"isJumpTheme":false,"ttsUrl":"https://static.tigerbbs.com/5f75423fef57b3e4f2608f693455e9be","symbols_score_info":{},"content_text":"随着变种病毒肆虐，新冠疫情在全球呈现复燃之势。更让人感到不安的是，有不少确诊病例是已经接种过疫苗的人群。\n例如，美国华裔体操运动员卡拉·埃克(Kara Eaker)和英国卫生大臣赛义德·贾维德(Sajid Javid)都是在接种疫苗后，被检测出新冠阳性，均被诊断为“突破性感染”(Breakthrough Infection)。\n那么到底什么是突破性感染？为何接种疫苗后仍会感染？这种现象有多普遍，又有多危险呢？美国范德堡大学医学中心项目协调员和员工科学家Sanjay Mishra近日对这些问题作出解读。\n什么是突破性感染？\n当人们在接种疫苗后被感染时，科学家称这些病例为“突破性”感染，因为病毒突破了疫苗提供的保护屏障。\n要知道所有的疫苗都不是100%有效的。例如，保护儿童免受脊髓灰质炎侵害的疫苗有效率在80%到90%左右，麻疹疫苗的有效率为94%。\n在新冠疫苗方面，据临床试验，辉瑞/BioNTech和Moderna的mRNA疫苗的有效性为94%-95%，该数值高于预期值。\n如何理解疫苗有效率？\n95%的疫苗效力并不意味着疫苗能保护95%的人，而其他5%的人会感染病毒。\n疫苗有效性衡量的是相对风险，即在相同的暴露条件下，将一组接种疫苗的人与一组未接种疫苗的人进行比较。假设在一个为期三个月的临床试验期间，每10000名未接种疫苗的人中有100人感染，同时，每10000名接种疫苗的人中有5人感染，那么疫苗的有效性为95%。\n也就是说，疫苗保护的是这100个（没接种疫苗且确定会感染）人群的95%，而不是整个10000人群的95%。\n突破性感染的现象有多普遍？\n随着Delta变种病毒的蔓延，突破性感染出现的频率略有些高于预期。但在已接种疫苗人群中，感染仍然非常罕见，且通常导致轻微或无症状。\n例如，在2021年1月1日至4月30日期间，美国46个州和地区向美国疾病控制与预防中心报告了10262例突破性感染。相比之下，同期共有1180万例确诊病例。截至2021年7月19日，美国全国已有1.59亿多人接种了新冠疫苗，其中5914人因突破性感染住院或死亡。\n此外， 2020年12月15日至2021年3月31日期间开展的一项研究显示，在258716名接受了辉瑞或Moderna两剂疫苗的退伍军人中，410人出现了突破性感染，占总数的0.16%。\n同样，纽约的一项研究发现，在2021年2月1日至4月30日期间，在126367名全面接种疫苗(主要是mRNA疫苗)的人中，出现了86例突破性感染，这占病例总数的1.2%，占完全接种人群的0.07%。\n突破性感染有多严重?\n美国疾病控制与预防中心（CDC）将疫苗突破性感染定义为，在完成FDA授权的COVID-19疫苗的全部推荐剂量后14天以上，鼻拭子可以检测到SARS-CoV-2 RNA或蛋白质。\n需要注意的是，突破性感染并不一定意味着患者感到不适——事实上，向美国CDC报告的突破性感染病例中，27%是无症状的。据了解，只有10%的突破感染者住院(有些是由于新冠以外的原因)，2%的人死亡。相比之下，在尚未开启疫苗接种的2020年春季，超过6%的确诊感染是致命的。\n在美国军事治疗设施进行的一项研究中，这些突破性感染没有导致住院治疗。在另一项研究中，仅注射一剂辉瑞疫苗后，COVID-19检测呈阳性的接种者体内的病毒含量比未接种且检测呈阳性的人少四分之一。\n什么情况下容易发生突破性感染？\n社区聚集性传播中，出现突破性感染的机率较大。\n在近距离接触的情况下，如在狭窄的工作空间、聚会、餐厅或体育场，感染可能性更大。突破性感染也更有可能发生在经常接触受感染患者的医务工作者中。\n性别、年龄、身体状况也都会影响感染机率。\n美国CDC的数据显示，突破性感染中女性占63%，原因尚不清楚。一些规模较小的研究也确定女性在突破性病例中占比较大。\n疫苗在老年人中引发的免疫反应较弱，而且随着年龄的增长，突破性感染的机会越来越高。在CDC追踪的突破性病例中，75%发生在65岁及以上的患者中。\n免疫功能低下或有高血压、糖尿病、心脏病、慢性肾脏和肺部疾病以及癌症等潜在疾病，会增加突破性感染的机会，并可能导致重症。\n例如，在一项研究中，与接种过疫苗的普通人群相比，完全接种过疫苗的器官移植受者发生突破性感染的可能性高82倍，突破性感染后住院和死亡的风险高485倍。\nDelta变种病毒的影响有多大？\n现有的疫苗主要是针对早期的毒株，而包括Delta在内的新变种更擅长于躲避目前疫苗产生的抗体。虽然现有疫苗仍然有效，但有效性有所降低。\n根据英国公共卫生部的数据，两剂mRNA疫苗预防Delta病毒的有效性仅为79%，而对早期Alpha病毒的有效性为89%。单剂疫苗对Delta毒株的有效性仅为35%。\n在接种率较高的以色列，完全接种辉瑞疫苗后，对于预防Delta变种导致重症的有效率仅为39%-40.5%，远低于早期估计的90%。\n以色列的研究结果表明，在6个月内，疫苗预防感染和症状性疾病的效力会下降。不过，好消息是，疫苗在预防由Delta毒株导致的住院(88%)和重症(91.4%)方面仍然非常有效。\n疫苗效果到底怎么样？\n截至2021年7月底，49.1%的美国人口，即略超过1.63亿人，已全面接种疫苗。近90%的65岁以上的美国人至少接种过一剂疫苗。\n科学家的模型表明，截至2021年6月底，疫苗接种可能挽救了美国大约27.9万人的生命，防止了多达125万人住院治疗。在英国，疫苗可能预防了约30300例死亡、46300例住院和815万例感染。在以色列，高接种率被认为是推动该国病例数较大流行高峰时下降77%，住院人数下降68%的主要原因。\n在美国，5月份因新冠肺炎死亡的1.8万多人中，只有150人接种了疫苗。\n正如美国国家过敏症和传染病研究所所长安东尼·福奇(Anthony Fauci)所说，美国正变得“几乎像两个美国”，分为接种疫苗和未接种疫苗两部分。那些没有完全接种疫苗的人仍然面临来自冠状病毒的风险。","kind":"highlight","is_publish_news":false,"is_publish_highlight":true,"is_publish_live":false,"is_publish_wemedia":null,"editions":null,"column":"","sentiment":"0","news_tag":"","news_rank":0,"symbols":[],"gpt_button":1,"need_auth":false,"code":"91000000","status":"200"},"commentList":[{"id":801773907,"gmtCreate":1627539053209,"gmtModify":1703491954533,"author":{"id":"3574164671299178","authorId":"3574164671299178","name":"飞鸟跌穴298884","avatar":"https://static.tigerbbs.com/0a86a1d7644d8cfdcbb622860fd749e7","vip":1,"crmLevel":11,"crmLevelSwitch":0,"authorIdStr":"3574164671299178","idStr":"3574164671299178"},"htmlText":"?","listText":"?","text":"?","images":[],"top":1,"highlighted":1,"essential":1,"paper":1,"likeSize":3,"commentSize":1,"repostSize":0,"link":"https://ttm.financial/post/801773907","repostId":2155977655,"repostType":4,"repost":{"id":"2155977655","kind":"highlight","pubTimestamp":1627537962,"share":"https://ttm.financial/m/news/2155977655?lang=en_US&edition=fundamental","pubTime":"2021-07-29 13:52","market":"hk","language":"zh","title":"Why do you still get infected after vaccination? How to understand vaccine effectiveness","url":"https://stock-news.laohu8.com/highlight/detail?id=2155977655","media":"华尔街见闻","summary":"95%的疫苗效力并不意味着疫苗能保护95%的人，而其他5%的人会感染病毒。","content":"<p>As the variant virus rages, COVID-19 pandemic is showing a resurgence around the world. What is even more disturbing is that many confirmed cases are people who have been vaccinated.</p><p>For example, Chinese-American gymnast Kara Eaker and British Health Secretary Sajid Sajid Javid both tested positive for the new crown after being vaccinated, and both were diagnosed with \"Breakthrough Infection\".</p><p>So what exactly is a breakthrough infection? Why do you still get infected after vaccination? How common is this phenomenon and how dangerous is it? Sanjay Mishra, project coordinator and staff scientist at Vanderbilt University Medical Center in the United States, recently explained these issues.</p><p><h2>What is a breakthrough infection?</h2>When people become infected after being vaccinated, scientists call these cases \"breakthrough\" infections because the virus breaks through the protective barrier provided by the vaccine.</p><p><b>Be aware that all vaccines are not 100% effective.</b>For example, vaccines that protect children from polio are around 80 to 90 percent effective, and measles vaccines are 94 percent effective.</p><p>In terms of COVID-19 vaccine, according to clinical trials,<a href=\"https://laohu8.com/S/PFE\">Pfizer</a>/The effectiveness of BioNTech and Moderna's mRNA vaccines is 94%-95%, which is higher than expected.</p><p><h2>How to understand vaccine effectiveness?</h2>95% vaccine efficacy doesn't mean that the vaccine protects 95% of people while the other 5% will catch the virus.</p><p>Vaccine effectiveness measures relative risk, which is comparing a group of vaccinated people to a group of unvaccinated people under the same exposure conditions. Assuming that during a three-month clinical trial, there are 100 infections for every 10,000 unvaccinated people, and at the same time, there are 5 infections for every 10,000 vaccinated people, then the vaccine is 95% effective.</p><p><b>In other words, the vaccine protects 95% of these 100 people (who are not vaccinated and sure to be infected), not 95% of the entire 10,000 people.</b></p><p><h2><b>How common are breakthrough infections?</b></h2>As the Delta variant spreads, breakthrough infections appear slightly more frequently than expected.<b>But among vaccinated people, infections are still very rare and often result in mild or asymptomatic cases.</b></p><p>For example, between January 1 and April 30, 2021, 46 U.S. states and territories reported 10,262 breakthrough infections to the U.S. Centers for Disease Control and Prevention. This compares to a total of 11.8 million confirmed cases over the same period. As of July 19, 2021, more than 159 million people nationwide have been vaccinated with COVID-19 vaccine, of which 5,914 have been hospitalized or died due to breakthrough infections.</p><p>Additionally, a study conducted between December 15, 2020, and March 31, 2021 showed that out of 258,716 veterans who received two doses of the Pfizer or Moderna vaccine, 410 had breakthrough infections, or 0.16% of the total.</p><p>Similarly, a New York study found 86 breakthrough infections among 126,367 people who were fully vaccinated (mainly mRNA vaccines) between February 1 and April 30, 2021, which represents 1.2% of the total number of cases and 0.07% of the fully vaccinated population.</p><p><h2>How serious is a breakthrough infection?</h2>The Centers for Disease Control and Prevention (CDC) defines vaccine breakthrough infection as a nasal swab that can detect SARS-CoV-2 RNA or protein more than 14 days after completing the full recommended dose of an FDA-authorized COVID-19 vaccine.</p><p>It's important to note that a breakthrough infection does not necessarily mean that the patient is feeling unwell-in fact, 27% of breakthrough infection cases reported to the US CDC are asymptomatic. It is understood that only 10% of breakthrough infections were hospitalized (some due to reasons other than COVID-19), and 2% died. In contrast, more than 6% of confirmed infections were fatal in spring 2020, when vaccination had not yet been opened.</p><p>These breakthrough infections did not lead to hospitalization in a study conducted at a U.S. military treatment facility.<b>In another study, after just one dose of the Pfizer vaccine, vaccinated people who tested positive for COVID-19 had a quarter less virus in their bodies than unvaccinated people who tested positive.</b></p><p><h2>Under what circumstances are breakthrough infections prone to occur?</h2>In community cluster transmission, the probability of breakthrough infection is high.</p><p>Infection is more likely in situations of close contact, such as in cramped workspaces, parties, restaurants, or stadiums. Breakthrough infections are also more likely to occur among healthcare workers who frequently come into contact with infected patients.</p><p><b>Gender, age, and physical condition also affect the infection rate.</b></p><p>According to CDC data, women account for 63% of breakthrough infections, and the reason is unclear. Some smaller studies have also determined that women account for a larger proportion of breakthrough cases.</p><p>The vaccine elicits a weaker immune response in older adults, and the chance of breakthrough infection increases as we age. Of the breakthrough cases tracked by the CDC, 75% occurred in patients 65 years and older.</p><p>Immunocompromised or underlying conditions such as hypertension, diabetes, heart disease, chronic kidney and lung disease, and cancer can increase the chance of breakthrough infections and can lead to severe illness.</p><p>For example, in one study, fully vaccinated organ transplant recipients were 82 times more likely to develop a breakthrough infection and had a 485 times higher risk of hospitalization and death following a breakthrough infection compared to the vaccinated general population.</p><p><h2>How big is the impact of the Delta variant?</h2>Existing vaccines mainly target earlier strains, while new variants, including Delta, are better at dodging the antibodies produced by current vaccines. While existing vaccines are still effective, their effectiveness has decreased.</p><p>According to Public Health England, two doses of the mRNA vaccine are only 79% effective in protecting against the Delta virus, compared to 89% effective against the earlier Alpha virus. The single-dose vaccine is only 35% effective against the Delta strain.</p><p>In Israel, which has a high vaccination rate, after being fully vaccinated with the Pfizer vaccine, the effective rate of preventing severe illness caused by the Delta variant is only 39%-40.5%, far lower than the early estimate of 90%.</p><p>The Israeli findings suggest that vaccines are less effective in preventing infections and symptomatic diseases within 6 months.<b>The good news, though, is that vaccines are still very effective at preventing hospitalizations (88%) and severe illness (91.4%) caused by the Delta strain.</b></p><p><h2>How effective is the vaccine?</h2>As of the end of July 2021, 49.1% of the U.S. population, or just over 163 million people, had been fully vaccinated. Nearly 90% of Americans over the age of 65 have received at least one dose of the vaccine.</p><p>Scientists'modelling suggests that vaccinations may have saved roughly 279,000 lives and prevented as many as 1.25 million hospitalizations in the United States by the end of June 2021. In the UK, vaccines may have prevented some 30,300 deaths, 46,300 hospitalizations and 8.15 million infections. In Israel, the high vaccination rate is believed to be the main reason for the 77% drop in case numbers and the 68% drop in hospitalizations in the country at the peak of the pandemic.</p><p><b>In the United States, only 150 of the more than 18,000 people who died due to novel coronavirus pneumonia in May were vaccinated.</b></p><p>As Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, puts it, the United States is becoming \"almost like two Americas,\" divided into vaccinated and unvaccinated parts. Those who are not fully vaccinated are still at risk from the coronavirus.</p>","source":"wallstreetcn_api","collect":0,"html":"<!DOCTYPE html>\n<html>\n<head>\n<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />\n<meta name=\"viewport\" content=\"width=device-width,initial-scale=1.0,minimum-scale=1.0,maximum-scale=1.0,user-scalable=no\"/>\n<meta name=\"format-detection\" content=\"telephone=no,email=no,address=no\" />\n<title>Why do you still get infected after vaccination? How to understand vaccine effectiveness</title>\n<style type=\"text/css\">\na,abbr,acronym,address,applet,article,aside,audio,b,big,blockquote,body,canvas,caption,center,cite,code,dd,del,details,dfn,div,dl,dt,\nem,embed,fieldset,figcaption,figure,footer,form,h1,h2,h3,h4,h5,h6,header,hgroup,html,i,iframe,img,ins,kbd,label,legend,li,mark,menu,nav,\nobject,ol,output,p,pre,q,ruby,s,samp,section,small,span,strike,strong,sub,summary,sup,table,tbody,td,tfoot,th,thead,time,tr,tt,u,ul,var,video{ font:inherit;margin:0;padding:0;vertical-align:baseline;border:0 }\nbody{ font-size:16px; line-height:1.5; color:#999; background:transparent; }\n.wrapper{ overflow:hidden;word-break:break-all;padding:10px; }\nh1,h2{ font-weight:normal; line-height:1.35; margin-bottom:.6em; }\nh3,h4,h5,h6{ line-height:1.35; margin-bottom:1em; }\nh1{ font-size:24px; }\nh2{ font-size:20px; }\nh3{ font-size:18px; }\nh4{ font-size:16px; }\nh5{ font-size:14px; }\nh6{ font-size:12px; }\np,ul,ol,blockquote,dl,table{ margin:1.2em 0; }\nul,ol{ margin-left:2em; }\nul{ list-style:disc; }\nol{ list-style:decimal; }\nli,li p{ margin:10px 0;}\nimg{ max-width:100%;display:block;margin:0 auto 1em; }\nblockquote{ color:#B5B2B1; border-left:3px solid #aaa; padding:1em; }\nstrong,b{font-weight:bold;}\nem,i{font-style:italic;}\ntable{ width:100%;border-collapse:collapse;border-spacing:1px;margin:1em 0;font-size:.9em; }\nth,td{ padding:5px;text-align:left;border:1px solid #aaa; }\nth{ font-weight:bold;background:#5d5d5d; }\n.symbol-link{font-weight:bold;}\n/* header{ border-bottom:1px solid #494756; } */\n.title{ margin:0 0 8px;line-height:1.3;color:#ddd; }\n.meta {color:#5e5c6d;font-size:13px;margin:0 0 .5em; }\na{text-decoration:none; color:#2a4b87;}\n.meta .head { display: inline-block; overflow: hidden}\n.head .h-thumb { width: 30px; height: 30px; margin: 0; padding: 0; border-radius: 50%; float: left;}\n.head .h-content { margin: 0; padding: 0 0 0 9px; float: left;}\n.head .h-name {font-size: 13px; color: #eee; margin: 0;}\n.head .h-time {font-size: 12.5px; color: #7E829C; margin: 0;}\n.small {font-size: 12.5px; display: inline-block; transform: scale(0.9); -webkit-transform: scale(0.9); transform-origin: left; -webkit-transform-origin: left;}\n.smaller {font-size: 12.5px; display: inline-block; transform: scale(0.8); -webkit-transform: scale(0.8); transform-origin: left; -webkit-transform-origin: left;}\n.bt-text {font-size: 12px;margin: 1.5em 0 0 0}\n.bt-text p {margin: 0}\n</style>\n</head>\n<body>\n<div class=\"wrapper\">\n<header>\n<h2 class=\"title\">\nWhy do you still get infected after vaccination? How to understand vaccine effectiveness\n</h2>\n<h4 class=\"meta\">\n<p class=\"head\">\n<strong class=\"h-name small\">华尔街见闻</strong><span class=\"h-time small\">2021-07-29 13:52</span>\n</p>\n</h4>\n</header>\n<article>\n<p>As the variant virus rages, COVID-19 pandemic is showing a resurgence around the world. What is even more disturbing is that many confirmed cases are people who have been vaccinated.</p><p>For example, Chinese-American gymnast Kara Eaker and British Health Secretary Sajid Sajid Javid both tested positive for the new crown after being vaccinated, and both were diagnosed with \"Breakthrough Infection\".</p><p>So what exactly is a breakthrough infection? Why do you still get infected after vaccination? How common is this phenomenon and how dangerous is it? Sanjay Mishra, project coordinator and staff scientist at Vanderbilt University Medical Center in the United States, recently explained these issues.</p><p><h2>What is a breakthrough infection?</h2>When people become infected after being vaccinated, scientists call these cases \"breakthrough\" infections because the virus breaks through the protective barrier provided by the vaccine.</p><p><b>Be aware that all vaccines are not 100% effective.</b>For example, vaccines that protect children from polio are around 80 to 90 percent effective, and measles vaccines are 94 percent effective.</p><p>In terms of COVID-19 vaccine, according to clinical trials,<a href=\"https://laohu8.com/S/PFE\">Pfizer</a>/The effectiveness of BioNTech and Moderna's mRNA vaccines is 94%-95%, which is higher than expected.</p><p><h2>How to understand vaccine effectiveness?</h2>95% vaccine efficacy doesn't mean that the vaccine protects 95% of people while the other 5% will catch the virus.</p><p>Vaccine effectiveness measures relative risk, which is comparing a group of vaccinated people to a group of unvaccinated people under the same exposure conditions. Assuming that during a three-month clinical trial, there are 100 infections for every 10,000 unvaccinated people, and at the same time, there are 5 infections for every 10,000 vaccinated people, then the vaccine is 95% effective.</p><p><b>In other words, the vaccine protects 95% of these 100 people (who are not vaccinated and sure to be infected), not 95% of the entire 10,000 people.</b></p><p><h2><b>How common are breakthrough infections?</b></h2>As the Delta variant spreads, breakthrough infections appear slightly more frequently than expected.<b>But among vaccinated people, infections are still very rare and often result in mild or asymptomatic cases.</b></p><p>For example, between January 1 and April 30, 2021, 46 U.S. states and territories reported 10,262 breakthrough infections to the U.S. Centers for Disease Control and Prevention. This compares to a total of 11.8 million confirmed cases over the same period. As of July 19, 2021, more than 159 million people nationwide have been vaccinated with COVID-19 vaccine, of which 5,914 have been hospitalized or died due to breakthrough infections.</p><p>Additionally, a study conducted between December 15, 2020, and March 31, 2021 showed that out of 258,716 veterans who received two doses of the Pfizer or Moderna vaccine, 410 had breakthrough infections, or 0.16% of the total.</p><p>Similarly, a New York study found 86 breakthrough infections among 126,367 people who were fully vaccinated (mainly mRNA vaccines) between February 1 and April 30, 2021, which represents 1.2% of the total number of cases and 0.07% of the fully vaccinated population.</p><p><h2>How serious is a breakthrough infection?</h2>The Centers for Disease Control and Prevention (CDC) defines vaccine breakthrough infection as a nasal swab that can detect SARS-CoV-2 RNA or protein more than 14 days after completing the full recommended dose of an FDA-authorized COVID-19 vaccine.</p><p>It's important to note that a breakthrough infection does not necessarily mean that the patient is feeling unwell-in fact, 27% of breakthrough infection cases reported to the US CDC are asymptomatic. It is understood that only 10% of breakthrough infections were hospitalized (some due to reasons other than COVID-19), and 2% died. In contrast, more than 6% of confirmed infections were fatal in spring 2020, when vaccination had not yet been opened.</p><p>These breakthrough infections did not lead to hospitalization in a study conducted at a U.S. military treatment facility.<b>In another study, after just one dose of the Pfizer vaccine, vaccinated people who tested positive for COVID-19 had a quarter less virus in their bodies than unvaccinated people who tested positive.</b></p><p><h2>Under what circumstances are breakthrough infections prone to occur?</h2>In community cluster transmission, the probability of breakthrough infection is high.</p><p>Infection is more likely in situations of close contact, such as in cramped workspaces, parties, restaurants, or stadiums. Breakthrough infections are also more likely to occur among healthcare workers who frequently come into contact with infected patients.</p><p><b>Gender, age, and physical condition also affect the infection rate.</b></p><p>According to CDC data, women account for 63% of breakthrough infections, and the reason is unclear. Some smaller studies have also determined that women account for a larger proportion of breakthrough cases.</p><p>The vaccine elicits a weaker immune response in older adults, and the chance of breakthrough infection increases as we age. Of the breakthrough cases tracked by the CDC, 75% occurred in patients 65 years and older.</p><p>Immunocompromised or underlying conditions such as hypertension, diabetes, heart disease, chronic kidney and lung disease, and cancer can increase the chance of breakthrough infections and can lead to severe illness.</p><p>For example, in one study, fully vaccinated organ transplant recipients were 82 times more likely to develop a breakthrough infection and had a 485 times higher risk of hospitalization and death following a breakthrough infection compared to the vaccinated general population.</p><p><h2>How big is the impact of the Delta variant?</h2>Existing vaccines mainly target earlier strains, while new variants, including Delta, are better at dodging the antibodies produced by current vaccines. While existing vaccines are still effective, their effectiveness has decreased.</p><p>According to Public Health England, two doses of the mRNA vaccine are only 79% effective in protecting against the Delta virus, compared to 89% effective against the earlier Alpha virus. The single-dose vaccine is only 35% effective against the Delta strain.</p><p>In Israel, which has a high vaccination rate, after being fully vaccinated with the Pfizer vaccine, the effective rate of preventing severe illness caused by the Delta variant is only 39%-40.5%, far lower than the early estimate of 90%.</p><p>The Israeli findings suggest that vaccines are less effective in preventing infections and symptomatic diseases within 6 months.<b>The good news, though, is that vaccines are still very effective at preventing hospitalizations (88%) and severe illness (91.4%) caused by the Delta strain.</b></p><p><h2>How effective is the vaccine?</h2>As of the end of July 2021, 49.1% of the U.S. population, or just over 163 million people, had been fully vaccinated. Nearly 90% of Americans over the age of 65 have received at least one dose of the vaccine.</p><p>Scientists'modelling suggests that vaccinations may have saved roughly 279,000 lives and prevented as many as 1.25 million hospitalizations in the United States by the end of June 2021. In the UK, vaccines may have prevented some 30,300 deaths, 46,300 hospitalizations and 8.15 million infections. In Israel, the high vaccination rate is believed to be the main reason for the 77% drop in case numbers and the 68% drop in hospitalizations in the country at the peak of the pandemic.</p><p><b>In the United States, only 150 of the more than 18,000 people who died due to novel coronavirus pneumonia in May were vaccinated.</b></p><p>As Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, puts it, the United States is becoming \"almost like two Americas,\" divided into vaccinated and unvaccinated parts. Those who are not fully vaccinated are still at risk from the coronavirus.</p>\n<div class=\"bt-text\">\n\n\n<p> source：<a href=\"https://wallstreetcn.com/articles/3636611\">华尔街见闻</a></p>\n\n\n</div>\n</article>\n</div>\n</body>\n</html>\n","type":0,"thumbnail":"https://static.tigerbbs.com/6e474d690ea02c536f0fd4c03fc3ddef","relate_stocks":{},"source_url":"https://wallstreetcn.com/articles/3636611","is_english":false,"share_image_url":"https://static.laohu8.com/e9f99090a1c2ed51c021029395664489","article_id":"2155977655","content_text":"随着变种病毒肆虐，新冠疫情在全球呈现复燃之势。更让人感到不安的是，有不少确诊病例是已经接种过疫苗的人群。\n例如，美国华裔体操运动员卡拉·埃克(Kara Eaker)和英国卫生大臣赛义德·贾维德(Sajid Javid)都是在接种疫苗后，被检测出新冠阳性，均被诊断为“突破性感染”(Breakthrough Infection)。\n那么到底什么是突破性感染？为何接种疫苗后仍会感染？这种现象有多普遍，又有多危险呢？美国范德堡大学医学中心项目协调员和员工科学家Sanjay Mishra近日对这些问题作出解读。\n什么是突破性感染？\n当人们在接种疫苗后被感染时，科学家称这些病例为“突破性”感染，因为病毒突破了疫苗提供的保护屏障。\n要知道所有的疫苗都不是100%有效的。例如，保护儿童免受脊髓灰质炎侵害的疫苗有效率在80%到90%左右，麻疹疫苗的有效率为94%。\n在新冠疫苗方面，据临床试验，辉瑞/BioNTech和Moderna的mRNA疫苗的有效性为94%-95%，该数值高于预期值。\n如何理解疫苗有效率？\n95%的疫苗效力并不意味着疫苗能保护95%的人，而其他5%的人会感染病毒。\n疫苗有效性衡量的是相对风险，即在相同的暴露条件下，将一组接种疫苗的人与一组未接种疫苗的人进行比较。假设在一个为期三个月的临床试验期间，每10000名未接种疫苗的人中有100人感染，同时，每10000名接种疫苗的人中有5人感染，那么疫苗的有效性为95%。\n也就是说，疫苗保护的是这100个（没接种疫苗且确定会感染）人群的95%，而不是整个10000人群的95%。\n突破性感染的现象有多普遍？\n随着Delta变种病毒的蔓延，突破性感染出现的频率略有些高于预期。但在已接种疫苗人群中，感染仍然非常罕见，且通常导致轻微或无症状。\n例如，在2021年1月1日至4月30日期间，美国46个州和地区向美国疾病控制与预防中心报告了10262例突破性感染。相比之下，同期共有1180万例确诊病例。截至2021年7月19日，美国全国已有1.59亿多人接种了新冠疫苗，其中5914人因突破性感染住院或死亡。\n此外， 2020年12月15日至2021年3月31日期间开展的一项研究显示，在258716名接受了辉瑞或Moderna两剂疫苗的退伍军人中，410人出现了突破性感染，占总数的0.16%。\n同样，纽约的一项研究发现，在2021年2月1日至4月30日期间，在126367名全面接种疫苗(主要是mRNA疫苗)的人中，出现了86例突破性感染，这占病例总数的1.2%，占完全接种人群的0.07%。\n突破性感染有多严重?\n美国疾病控制与预防中心（CDC）将疫苗突破性感染定义为，在完成FDA授权的COVID-19疫苗的全部推荐剂量后14天以上，鼻拭子可以检测到SARS-CoV-2 RNA或蛋白质。\n需要注意的是，突破性感染并不一定意味着患者感到不适——事实上，向美国CDC报告的突破性感染病例中，27%是无症状的。据了解，只有10%的突破感染者住院(有些是由于新冠以外的原因)，2%的人死亡。相比之下，在尚未开启疫苗接种的2020年春季，超过6%的确诊感染是致命的。\n在美国军事治疗设施进行的一项研究中，这些突破性感染没有导致住院治疗。在另一项研究中，仅注射一剂辉瑞疫苗后，COVID-19检测呈阳性的接种者体内的病毒含量比未接种且检测呈阳性的人少四分之一。\n什么情况下容易发生突破性感染？\n社区聚集性传播中，出现突破性感染的机率较大。\n在近距离接触的情况下，如在狭窄的工作空间、聚会、餐厅或体育场，感染可能性更大。突破性感染也更有可能发生在经常接触受感染患者的医务工作者中。\n性别、年龄、身体状况也都会影响感染机率。\n美国CDC的数据显示，突破性感染中女性占63%，原因尚不清楚。一些规模较小的研究也确定女性在突破性病例中占比较大。\n疫苗在老年人中引发的免疫反应较弱，而且随着年龄的增长，突破性感染的机会越来越高。在CDC追踪的突破性病例中，75%发生在65岁及以上的患者中。\n免疫功能低下或有高血压、糖尿病、心脏病、慢性肾脏和肺部疾病以及癌症等潜在疾病，会增加突破性感染的机会，并可能导致重症。\n例如，在一项研究中，与接种过疫苗的普通人群相比，完全接种过疫苗的器官移植受者发生突破性感染的可能性高82倍，突破性感染后住院和死亡的风险高485倍。\nDelta变种病毒的影响有多大？\n现有的疫苗主要是针对早期的毒株，而包括Delta在内的新变种更擅长于躲避目前疫苗产生的抗体。虽然现有疫苗仍然有效，但有效性有所降低。\n根据英国公共卫生部的数据，两剂mRNA疫苗预防Delta病毒的有效性仅为79%，而对早期Alpha病毒的有效性为89%。单剂疫苗对Delta毒株的有效性仅为35%。\n在接种率较高的以色列，完全接种辉瑞疫苗后，对于预防Delta变种导致重症的有效率仅为39%-40.5%，远低于早期估计的90%。\n以色列的研究结果表明，在6个月内，疫苗预防感染和症状性疾病的效力会下降。不过，好消息是，疫苗在预防由Delta毒株导致的住院(88%)和重症(91.4%)方面仍然非常有效。\n疫苗效果到底怎么样？\n截至2021年7月底，49.1%的美国人口，即略超过1.63亿人，已全面接种疫苗。近90%的65岁以上的美国人至少接种过一剂疫苗。\n科学家的模型表明，截至2021年6月底，疫苗接种可能挽救了美国大约27.9万人的生命，防止了多达125万人住院治疗。在英国，疫苗可能预防了约30300例死亡、46300例住院和815万例感染。在以色列，高接种率被认为是推动该国病例数较大流行高峰时下降77%，住院人数下降68%的主要原因。\n在美国，5月份因新冠肺炎死亡的1.8万多人中，只有150人接种了疫苗。\n正如美国国家过敏症和传染病研究所所长安东尼·福奇(Anthony Fauci)所说，美国正变得“几乎像两个美国”，分为接种疫苗和未接种疫苗两部分。那些没有完全接种疫苗的人仍然面临来自冠状病毒的风险。","news_type":1,"symbols_score_info":{}},"isVote":1,"likeStatus":false,"favoriteStatus":false,"reportStatus":false,"tweetType":1,"comments":[{"id":5372711,"gmtCreate":1627598149174,"gmtModify":1663231688034,"authorId":3578402372027784,"author":{"id":3578402372027784,"idStr":"3578402372027784","authorId":3578402372027784,"name":"隨缘呗","avatar":"https://static.tigerbbs.com/d112fbb709c85fd78977ffa119acab4d","vip":1,"crmLevel":12,"crmLevelSwitch":0,"individualDisplayBadges":[]},"repliedAuthorId":0,"objectId":801773907,"type":1,"supId":0,"prevId":0,"content":"[思考]","text":"[思考]","html":"[思考]"}],"langContent":"EN"}],"isCommentEnd":false,"newsSizeData":{"likeSize":10,"commentSize":1,"repostSize":0,"favoriteSize":0,"likeStatus":false,"favoriteStatus":false},"APP":{"userAgent":"Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)","isDev":false,"isTTM":true,"deviceId":"web-server-community-laohu8-v3","version":"4.35.12","shortVersion":"4.35.12","platform":"web","vendor":"web","appName":"ttm","isIOS":false,"isAndroid":false,"isTiger":false,"isTHS":false,"isWeiXin":false,"isWeiXinMini":false,"isWeiBo":false,"isQQ":false,"isBaiduSwan":false,"isBaiduBox":false,"isDingTalk":false,"isToutiao":false,"isOnePlus":false,"isHuaWei":false,"isXiaomi":false,"isXiaomiWebView":false,"isOppo":false,"isVivo":false,"isSamsung":false,"isMobile":false},"href":"/m/news/2155977655","isCrawlerRequest":true}