ファイザー製ワクチン、１０万人に１人に重いアレルギー反応　米研究

【ワシントンＡＦＰ＝時事】米保健当局は6日、米製薬大手ファイザーと独製薬ビオンテックが共同開発した新型コロナウイルスワクチンの接種を受けた人のうち、10万人に1人ほどの割合で重篤なアレルギー反応が起きていたと発表した。一方で、同当局は予防接種がもたらす恩恵はこの既知のリスクをはるかに上回ることを強調した。（写真は米製薬大手ファイザー・独製薬ビオンテック共同開発の新型コロナウイルスワクチンを持つ医療従事者）
　このデータは米疾病対策センター（ＣＤＣ）が明らかにしたもので、昨年１２月１４日から２３日の間に実施したと報告されている１８９万３３６０本の接種後、アナフィラキシーの症例２１件を記録している。
　ＣＤＣのナンシー・メッソニエ氏は記者団に「接種１００万人当たり１１・１人の割合でアナフィラキシーの症状が起きている」と語った。
　インフルエンザワクチンでは、１００万人当たり約１・３人にアナフィラキシー症状が発生しており、ファイザーのワクチンはおおむねこの１０倍となる。
　メッソニエ氏は、アナフィラキシーの症例はそれでも「極めてまれ」であって、ワクチン接種を受けることは国民にとって最善策であることに変わらないと指摘。とりわけ国民の健康にとって極めて大きな脅威である新型コロナウイルス感染症の流行下では、なおさらそうだと強調した。
　「幸いなことに、われわれはアナフィラキシーの治療法を知っており、予防接種の施設には接種を実施する職員がアナフィラキシー治療に当たるよう、対策がきちんと確立されている」とメッソニエ氏は語った。
　アナフィラキシー症状を起こした人のうち４人（１９％）は入院し、うち３人は集中治療室に入った。あとの１７人（８１％）は救急科で治療を受けた。調査時には１人を除いて全員が退院または回復したことが分かっており、死者は出ていない。
　症状は発疹、喉の詰まり、舌の腫れ、じんましん、呼吸困難、声のかすれ、唇の腫れ、吐き気、長引く乾いたせきなどだ。
　メッソニエ氏はアレルギーの原因を突き止める調査が進行中だと述べた。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2021/01/08-13:48）

Roughly one in a hundred thousand people who received the Pfizer-BioNTech Covid-19 vaccine have had severe allergic reactions, US health officials said Wednesday while stressing that the benefits of immunization greatly outweigh the known risks.
The data comes from the Centers for Disease Control and Prevention, which documented 21 cases of anaphylaxis after administration of a reported 1,893,360 shots from December 14 to December 23.
This averages out to a rate of 11.1 anaphylaxis cases per one million doses administered, senior CDC official Nancy Messonnier told reporters.
By comparison, flu vaccines cause about 1.3 anaphylaxis cases per million doses administered, and so the rate of anaphylaxis for the Pfizer vaccine is roughly ten times greater.
Messonnier added that anaphylaxis cases were still exceedingly rare and it remains in people's best interest to take the vaccine, particularly in the context of the Covid-19 pandemic that is a far greater danger to their health.
A good value proposition for someone to get vaccinated is their risk from Covid and poor outcomes from Covid is still more than the risk of a severe outcome from the vaccine, she said.
Fortunately, we know how to treat anaphylaxis, and we've put provisions in place to ensure that at immunization sites, the folks administering the vaccine are ready to treat anaphylaxis.
The 21 cases ranged in age from 27 to 60 years old, with a median age of 40, and all but two were treated with epinephrine.
Nineteen of the cases (90 percent) occurred in females, and the median onset time of symptoms was 13 minutes, but ranged from two to 150 minutes.
Four (19 percent) of patients were hospitalized, including three in intensive care, and 17 (81 percent) were treated in an emergency department. All but one was known to have been discharged home or recovered at the time of the study, and there were no deaths.
Symptoms included rash, sensation of throat closure, swollen tongue, hives, difficulty breathing, hoarseness, swollen lips, nausea and persistent dry cough.
- Investigations ongoing -
The US has so far authorized two vaccines for emergency use -- one developed by Pfizer and the other by Moderna.
Both are based on cutting-edge mRNA (messenger ribonucleic acid) technology and authorities have attached similar warning labels to both, which advise that people who have a known history of allergic reactions to the vaccines' ingredients avoid taking them.
People who have a severe reaction to the first dose are also asked to not take a second dose.
Messonnier said that investigations were underway to determine what may be the cause of the allergies.
There is not enough data yet to know what the rate of anaphylaxis is for the Moderna vaccine, which was authorized in the US a week after the Pfizer shot, or whether a significant difference between the two vaccines will emerge.
One preliminary hypothesis for the reactions is the presence of the compound polyethylene glycol (PEG), which has never before been used in an approved vaccine, but is found in everyday products including laxatives, shampoos and toothpastes.
Both the Pfizer and Moderna vaccines use PEG molecules as part of the protective casing around their main ingredient, the mRNA that carries genetic instructions to cells.