{"id":8467,"date":"2020-03-23T12:59:17","date_gmt":"2020-03-23T12:59:17","guid":{"rendered":"http:\/\/www.drknowhk.org\/?p=8467"},"modified":"2024-03-13T16:40:32","modified_gmt":"2024-03-13T16:40:32","slug":"can-a-century-old-tb-vaccine-steel-the-immune-system-against-the-new-coronavirus","status":"publish","type":"post","link":"https:\/\/www.drknowhk.org\/mo\/can-a-century-old-tb-vaccine-steel-the-immune-system-against-the-new-coronavirus\/","title":{"rendered":"Can a century-old TB vaccine steel the immune system against the new coronavirus?"},"content":{"rendered":"

\u5c0d\u4e0d\u8d77\uff0c\u6b64\u5185\u5bb9\u53ea\u9069\u7528\u65bcEnglish<\/a>\u3002<\/p>

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KWANGMOOZAA\/ISTOCK<\/span><\/strong><\/p>\n

Vaccination with bacillus Calmette-Gu\u00e9rin leads to a small pustule that can develop into a scar.<\/p>\n<\/div>\n

Researchers in four countries will soon start a clinical trial of an unorthodox approach to the new coronavirus. They will test whether a century-old vaccine against tuberculosis (TB), a bacterial disease, can rev up the human immune system in a broad way, allowing it to better fight the virus that causes coronavirus disease 2019 and, perhaps, prevent infection with it altogether.\u00a0The studies will be done in physicians and nurses, who are at higher risk of becoming infected with the respiratory disease than the general population, and in the elderly, who are at higher risk of serious illness if they become infected.<\/p>\n

A team in the Netherlands will kick off the first of the trials this week. They will recruit 1000 health care workers in eight Dutch hospitals who will either receive the vaccine, called bacillus Calmette-Gu\u00e9rin (BCG), or a placebo.<\/p>\n

BCG contains a live, weakened strain of\u00a0Mycobacterium bovis<\/em>,\u00a0<\/em>a cousin of\u00a0M. tuberculosis<\/em>,\u00a0<\/em>the microbe that causes TB. (The vaccine is named after French microbiologists Albert Calmette and Camille Gu\u00e9rin, who developed it in the early 20th\u00a0century.) The vaccine is given to children in their first year of life in most countries of the world, and is safe and cheap\u2014but far from perfect: It prevents about 60% of TB cases in children on average, with large differences between countries.<\/p>\n

Vaccines generally raise immune responses specific to a targeted pathogen, such as antibodies that bind and neutralize one type of virus but not others. But BCG may also increase the ability of the immune system to fight off pathogens other than the TB bacterium, according to clinical and observational studies published over several decades by Danish researchers Peter Aaby and Christine Stabell Benn, who live and work in Guinea-Bissau.\u00a0They concluded<\/a><\/strong>\u00a0the vaccine prevents about 30% of infections with any known pathogen, including viruses, in the first year after it\u2019s given. The studies published in this field have been criticized for their methodology, however;\u00a0a 2014 review<\/a>\u00a0<\/strong>ordered by the World Health Organization concluded that BCG appeared to lower overall mortality in children, but rated confidence in the findings as \u201cvery low.\u201d\u00a0A\u00a02016 review<\/a>\u00a0<\/strong>was a bit more positive about BCG\u2019s potential benefits\u00a0but said randomized trials were needed.<\/p>\n

Since then, the clinical evidence has strengthened and several groups have made important steps investigating how BCG may generally boost the immune system. Mihai Netea, an infectious disease specialist at Radboud University Medical Center, discovered that the vaccine may defy textbook knowledge of how immunity works.<\/p>\n

When a pathogen enters the body, white blood cells of the \u201cinnate\u201d\u00a0arm of the immune system attack it first; they may handle up to 99% of infections. If these cells fail, they call in the \u201cadaptive\u201d immune system, and T cells and antibody-producing B cells start to divide\u00a0to join the fight. Key to this is that certain T cells or antibodies are specific to the pathogen; their presence is amplified the most. Once the pathogen is eliminated, a small portion of these pathogen-specific cells transform into memory cells that speed up T cell and B cell production the next time the same pathogen attacks. Vaccines are based on this mechanism of immunity.<\/p>\n

The innate immune system, composed of white blood cells such as macrophages, natural killer cells, and neutrophils, was supposed to have no such memory. But Netea\u2019s team discovered that BCG, which can remain alive in the human skin for up to several months, triggers not only\u00a0Mycobacterium<\/em>-specific memory B and T cells, but also stimulates the innate blood cells for a prolonged period. \u201cTrained immunity,\u201d\u00a0Netea and colleagues call it<\/a><\/strong>. In a\u00a0randomized placebo-controlled study<\/strong><\/a>\u00a0published in 2018, the team showed that BCG vaccination protects against experimental infection with a weakened form of the yellow fever virus, which is used as a vaccine.<\/p>\n

Together with Evangelos Giamarellos from the University of Athens, Netea has set up a study in Greece to see whether BCG can increase resistance to infections overall in elderly people. He is planning to start a similar study in the Netherlands soon. The trial was designed before the new coronavirus emerged, but the pandemic may reveal BCG\u2019s broad effects more clearly, Netea says.<\/p>\n

For the health care worker study, Neeta teamed up with epidemiologist and microbiologist Marc Bonten of UMC Utrecht. \u201cThere is a lot of enthusiasm to participate,\u201d among the workers, Bonten says.\u00a0The team decided not to use actual infection with coronavirus as the study outcome, but \u201cunplanned absenteeism.\u201d \u201cWe don\u2019t have a large budget and it won\u2019t be feasible to visit the sick professionals at home,\u201d Bonten says. Looking at absenteeism has the advantage that any beneficial effects of the BCG vaccine on influenza and other infections may be captured as well, he says.<\/p>\n

Although the study is randomized, participants will likely know if they got the vaccine instead of a placebo. BCG often causes a pustule at the injection site that may persist for months, usually resulting in a scar. But the researchers will be blinded to which arm of the study\u2014vaccine or placebo\u2014a person is in.<\/p>\n

A research group at the University of Melbourne\u00a0is setting up a BCG study among health care workers using the exact same protocol. Another research group at the University of Exeter will do a similar study in the elderly. And a team at the Max Planck Institute for Infection Biology last week announced that\u2014inspired by Netea\u2019s work\u2014it will embark on\u00a0a similar trial<\/a><\/strong>\u00a0in elderly people and health workers with VPM1002, a genetically modified version of BCG that has not yet been approved for use against TB.<\/p>\n

Eleanor Fish, an immunologist at the of the University of Toronto, says the vaccine probably won\u2019t eliminate infections with the new coronavirus completely, but is likely to dampen its impact on individuals. Fish says she\u2019d take the vaccine herself if she could get a hold of it, and even wonders whether it\u2019s ethical to withhold its potential benefits from trial subjects in the placebo arm.<\/p>\n

But Netea says the randomized design is critical: \u201cOtherwise we would never know if this is good for people.\u201d The team may have answers within a few months.
\n\u985e\u578b: \u6587\u7ae0
\n\u4f5c\u8005: Jop de Vrieze
\n\u51fa\u8655: Science
\n\u9023\u7d50: https:\/\/www.sciencemag.org\/news\/2020\/03\/can-century-old-tb-vaccine-steel-immune-system-against-new-coronavirus<\/a>
\n<\/p>","protected":false},"excerpt":{"rendered":"

\u5c0d\u4e0d\u8d77\uff0c\u6b64\u5185\u5bb9\u53ea\u9069\u7528\u65bcEnglish<\/a>\u3002<\/p>\n

A team in the Netherlands will kick off the first of the trials this week. They will recruit 1000 health care workers in eight Dutch hospitals who will either receive the vaccine, called bacillus Calmette-Gu\u00e9rin (BCG), or a placebo……<\/p>\n","protected":false},"author":1,"featured_media":2919,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[57],"tags":[],"class_list":["post-8467","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-expert-commentary-announcement"],"_links":{"self":[{"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/posts\/8467","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/comments?post=8467"}],"version-history":[{"count":1,"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/posts\/8467\/revisions"}],"predecessor-version":[{"id":8468,"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/posts\/8467\/revisions\/8468"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/media\/2919"}],"wp:attachment":[{"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/media?parent=8467"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/categories?post=8467"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.drknowhk.org\/mo\/wp-json\/wp\/v2\/tags?post=8467"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}