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<<   作成日時 : 2009/03/19 20:18   >>

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画像 胎児に深刻な問題を起こすサイトメガロウイルスの実験的なワクチンにより、予防接種後3年半で50%感染リスクを減らしたと、新たな研究で判明した。専門家の多くは母体感染防止は非常に難しいだろうと思われていたため、多くの点で驚くべき結果であるとアラバマ大小児科の Dr. Robert Pass言う。
 サイトメガロウイルスCMVは子宮内で静かである一方胎児感染を起こし、毎年約8,000人の乳幼児に、重症聴力障害、精神運動障害を起こす。ウイルスはどこにでもいて、容易に広がる。研究者が、有効なワクチン開発がとても難しい理由の一つはウイルスが人の免疫系からの攻撃に順応することだろうと言う。
 水痘とはしかのようなウイルス感染と違って、初期の感染から何年も経ってからCMVに再感染する可能性がある。誰でもCMVに感染し、健康な成人と子供は通常伝染の徴候を示さない。
 新しいワクチンは、実験的なアジュバント(効力を増強するためにワクチンに追加される物質)と結合された1つのCMVたんぱく質から作らる。
 40才以下で出産歴がありCMVに感染していない464人の女性にたいして第2相の臨床試験である。半数がワクチン、残りはプラセーボを3回、開始時・1ヶ月後・6ヶ月後に投与した。42ヶ月の経過で、ワクチン群で18人、プラセーボ群で31人がCMVに感染した。統計学的には、ワクチン接種で感染が約半分になったことになる。
 NIH米国国立予防衛生研究所が資金のほとんどを提供した。ワクチン製造はSanofi Pasteurが行った。
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Trial Vaccine May Protect Against Serious Viral Infection
Women given injection could cut risk for CMV in half, study suggests
By Serena Gordon, HealthDay Reporter
http://health.msn.com/kids-health/articlepage.aspx?cp-documentid=100234890

Women given injection could cut risk for CMV in half, study suggests.

WEDNESDAY, March 18 (HealthDay News) -- Women who were given an experimental vaccine for a viral infection that can cause serious problems in babies, known as cytomegalovirus, reduced their risk of infection by 50 percent for as long as three and half years after vaccination, according to new research.

"In many ways, this was a surprising result," said the lead author of the study, Dr. Robert Pass, a professor of pediatrics at the University of Alabama at Birmingham. "Many people in the field felt it would be very difficult to prevent infection in mothers. We thought the best we could hope for was a vaccine for women that would prevent infection in a baby."

Results of the study are published in the March 19 issue of the New England Journal of Medicine.

Cytomegalovirus, or CMV, causes severe hearing, mental or movement impairments each year in about 8,000 infants who develop the infection while still in the womb, according to the National Institute of Allergy and Infectious Diseases.

The virus is very common and spreads easily, according to Pass. He said one reason researchers thought an effective vaccine would be so difficult to develop was that the virus adapts to attacks from the human immune system. And unlike infection from such viruses as chickenpox and measles, people can be re-infected with CMV many years after an initial infection.

Anyone can develop a CMV infection, and healthy adults and children usually don't show symptoms of the infection.

The new vaccine is made from a single CMV protein that was combined with an experimental adjuvant, a substance that's added to vaccines to boost their efficacy.

The study was a phase 2 trial that included 464 women, all younger than 40 who had given birth in the past year and had not been infected with CMV. Half were given the vaccine, and the other half were injected with a placebo. Three doses were given: at the start of the study, a month later, and again at six months.

In the first year, 49 infections with CMV occurred, the study reported. In the placebo group, 31 women were infected with CMV, compared with 18 who had been given the vaccine.

Using a statistical model, the researchers estimated that women given the vaccine would be half as likely to develop a CMV infection over a 42-month period as those given a placebo.

Dr. Navid Mootabar, director of gynecology surgery and associate chief of obstetrics and gynecology at Northern Westchester Hospital in Mt. Kisco, N.Y., described the study as "very promising."

"If we can reduce the risk of a pregnant woman acquiring CMV, then we will reduce the many neurologic and congenital risks than CMV poses to a growing fetus," he said. "However, further larger studies will be needed to ensure the safety and efficacy of the vaccine before we should recommend it to all women."

Most of the funding for the study came from the U.S. National Institutes of Health, Pass said. Sanofi Pasteur, which makes the vaccine, also helped fund the study and provided the vaccine.

Pass said that he was not aware of specific plans to conduct a phase 3 trial. But he said that, given the results, he expects the pharmaceutical company to move forward with development of the vaccine.

More information

The U.S. Centers for Disease Control and Prevention has more on CMV infections.
SOURCES: Robert Pass, M.D., professor of pediatrics, University of Alabama at Birmingham School of Medicine and Children's Hospital of Alabama; Navid Mootabar, M.D., director, gynecology surgery, and associate chief, obstetrics and gynecology, Northern Westchester Hospital, Mt. Kisco, N.Y.; March 19, 2009, New England Journal of Medicine

Copyright © 2009 ScoutNews, LLC. All rights reserved.

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NEMJ Volume 360:1191-1199 March 19, 2009 Number 12

Vaccine Prevention of Maternal Cytomegalovirus Infection
Robert F. Pass, M.D., Changpin Zhang, M.D., Ashley Evans, M.D., Tina Simpson, M.D., William Andrews, M.D., Meei-Li Huang, Ph.D., Lawrence Corey, M.D., Janie Hill, R.N., Elizabeth Davis, R.N., M.P.H., Cynthia Flanigan, B.S., and Gretchen Cloud, M.S.

ABSTRACT

Background Congenital infection with cytomegalovirus (CMV) is an important cause of hearing, cognitive, and motor impairments in newborns.

Methods In this phase 2, placebo-controlled, randomized, double-blind trial, we evaluated a vaccine consisting of recombinant CMV envelope glycoprotein B with MF59 adjuvant, as compared with placebo. Three doses of the CMV vaccine or placebo were given at 0, 1, and 6 months to CMV-seronegative women within 1 year after they had given birth. We tested for CMV infection in the women in quarterly tests during a 42-month period, using an assay for IgG antibodies against CMV proteins other than glycoprotein B. Infection was confirmed by virus culture or immunoblotting. The primary end point was the time until the detection of CMV infection.

Results We randomly assigned 234 subjects to receive the CMV vaccine and 230 subjects to receive placebo. A scheduled interim analysis led to a stopping recommendation because of vaccine efficacy. After a minimum of 1 year of follow-up, there were 49 confirmed infections, 18 in the vaccine group and 31 in the placebo group. Kaplan–Meier analysis showed that the vaccine group was more likely to remain uninfected during a 42-month period than the placebo group (P=0.02). Vaccine efficacy was 50% (95% confidence interval, 7 to 73) on the basis of infection rates per 100 person-years. One congenital infection among infants of the subjects occurred in the vaccine group, and three infections occurred in the placebo group. There were more local reactions (pain, erythema, induration, and warmth) and systemic reactions (chills, arthralgias, and myalgias) in the vaccine group than in the placebo group.

Conclusions CMV glycoprotein B vaccine has the potential to decrease incident cases of maternal and congenital CMV infection. (ClinicalTrials.gov number, NCT00125502 [ClinicalTrials.gov] .)

Source Information

From the Departments of Pediatrics (R.F.P., C.Z., T.S., J.H.), Obstetrics and Gynecology (W.A.), and Medicine (C.F., G.C.), University of Alabama at Birmingham, Birmingham; the Department of Pediatrics, University of Alabama College of Community Health Sciences, Tuscaloosa (A.E., E.D.); and the Departments of Laboratory Medicine (M.-L.H., L.C.) and Medicine (L.C.), University of Washington; and the Fred Hutchinson Cancer Research Center (M.-L.H., L.C.) ― both in Seattle.

Address reprint requests to Dr. Pass at Children's Hospital, 1600 7th Ave. S., CHB 309, Birmingham, AL 35233, or at rpass@peds.uab.edu.

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