2014年07月29日

天然痘

前回、種痘伝来の読書記について書きました。いろいろ調べていくと、とても興味深く、いろいろな本を買い込んでしまいました。
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天然痘オタクまっしぐらでございます。

しかし、過去の病気だと思われている天然痘ですが、こんなホットなニュースがありました。
天然痘ウイルスは、いままで世界で2カ所の、高度封じ込めレベルの研究室に保管されていました。ところが、NIHの古い倉庫を片づけていたら、ウイルスの入った瓶があった!と。

CDC Media Statement on Newly Discovered Smallpox Specimens

On July 1, 2014, the National Institutes of Health (NIH) notified the appropriate regulatory agency, the Division of Select Agents and Toxins (DSAT) of the Centers for Disease Control and Prevention (CDC), that employees discovered vials labeled ”variola,” commonly known as smallpox, in an unused portion of a storage room in a Food and Drug Administration (FDA) laboratory located on the NIH Bethesda campus.


何てこったい!ですね。
なにしろ、この天然痘ウイルスは、バイオテロに使われる危険が以前から示唆されていて、厳重に保管されていたのですから!臨床医学雑誌の最高峰 The New England Journal of Medicine にも、総説が掲載されたことがありました。
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日本では、1976年に種痘が廃止されたので、約40歳未満の人はほとんどが天然痘に対する免疫がありません。しかも、過去よりも都市化が進んでいますから、発生した場合は大流行することが予想されます。

Guardian 紙も『厳重保管されていた天然痘ウイルスを廃棄しようか、という議論は近視眼的だったね』という論調。何しろ、ラボの倉庫にコロンとウイルスが転がっているのだから、世界中のどこにウイルスがあってもおかしくないですものね。

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日本では、種痘は中止されていますが、天然痘テロのリスクに対して、ワクチンの国家備蓄をおこなっています。いまはワクチンは化血研が製造しています。ちゃんと効果も確認済み!

Original Contribution | March 11, 2009

Clinical and Immunological Response to Attenuated Tissue-Cultured Smallpox Vaccine LC16m8

Context The attenuated, tissue-cultured, third-generation smallpox vaccine LC16m8 was administered to vaccinia-naive infants in Japan during the 1970s without serious adverse events. It is a good candidate for use as part of a prevention plan for bioterrorism.

Objective To assess the immunogenicity and frequency of adverse events of LC16m8 vaccine in unvaccinated and previously vaccinated adults.

Design, Setting, and Participants Between 2002 and 2005 we vaccinated and revaccinated 1529 and 1692 adults, respectively, in the Japan Self-Defense Forces with LC16m8 vaccine, given intraepidermally using a bifurcated needle. Vaccinees were examined 10 to 14 days after vaccination to determine if they had developed a major skin reaction (“take”). Neutralizing antibody responses among 200 participants were assessed using a plaque-reduction neutralization test 30 days postvaccination. We monitored vaccinees for adverse events for 30 days postvaccination.

Main Outcome Measures Documentation of a vaccine take, presence of neutralizing antibody response, and frequency of adverse events.

Results The proportions of take in vaccinia-naive and previously vaccinated individuals were 1443 of 1529 (94.4% [95% confidence interval {CI}, 93.2%-95.9%] and 1465 of 1692 (86.6% [95% CI, 85.0%-88.2%]), respectively. Seroconversion or an effective booster response among the individuals with take was elicited in 37 of 41 (90.2% [95% CI, 81.2%-99.3%]) vaccinia-naive participants and in 93 of 155 (60.0% [95% CI, 52.3%-67.7%]) previously vaccinated participants. One case of allergic dermatitis and another of erythema multiforme, both of which were mild and self-limited, were suspected to be caused by vaccination. No severe adverse events were observed.

Conclusion Administration of an attenuated tissue-cultured smallpox vaccine (LC16m8) to healthy adults was associated with high levels of vaccine take and seroconversion in those who were vaccinia-naive and yielded an effective booster response in some previously vaccinated individuals.
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