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zoom RSS ロタウイルス予防接種により百万人の子どもを救う/ワクチン

<<   作成日時 : 2010/01/28 21:00   >>

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 2つの新たな研究により、乳幼児へのロタウイルス予防接種により発展途上国で数百万人の子どもを救うことができるだろうという。
 マラウイと南アフリカで行われた研究によれば、予防接種により61%以上も重症ロタウイルス感染を減らせた。メキシコでの研究結果では、2003-2006年に比べて2009年の11ヶ月以下の子どもの下痢による死亡が66%以上減少した。メキシコ健康省は2006-2007年に全国的なロタウイルスワクチン予防接種プログラムを始めた。
 発展途上国では子どもの死亡原因の2番目が下痢による。WHOによれば、毎年50万人以上の子どもがロタウイルス感染で死亡していて、そのうち半数はサハラ以南のアフリカである。ひどい下痢で入院する子どもの約40%はロタウイルスによると推計されている。
 米国でも3才以下の子どもでは良くみられるが、医療や経口補水剤によりほとんど死亡することはない。CDCは、米国では2/4/6ヶ月にワクチン接種するよう勧奨している。
 入手可能なロタウイルスワクチンは経口生ワクチンである。
 マラウイでは有効性は49%で、南アフリカでは約77%だった。
 WHOは生後6-15週に最初の接種を受けるよう勧奨している。
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ロタウイルス・ワクチンを子どもの定期接種に WHO推奨
http://kurie.at.webry.info/200906/article_6.html
ロタウイルスワクチンで大きな効果/米国医療事情
http://kurie.at.webry.info/200806/article_40.html
小児に対するロタウイルス・ワクチンRotarix 認可/米国
http://kurie.at.webry.info/200804/article_22.html
ロタウイルス感染症(乳児下痢症) ワクチン接種を検討
http://kurie.at.webry.info/200706/article_83.html
世界の子どもの死亡率が低下
http://kurie.at.webry.info/200709/article_27.html
ポリオ撲滅に2億ドル/ゲイツ財団
http://kurie.at.webry.info/200711/article_43.html
ゲイツ財団、結核対策に新たな資金提供
http://kurie.at.webry.info/200709/article_49.html
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Rotavirus Vaccine Could Save Millions of Children Worldwide
Trials in Africa, Mexico show shot protects from the common diarrhea-causing disease
By Jennifer ThomasHealthDay Reporter
http://health.msn.com/health-topics/digestive-health/articlepage.aspx?cp-documentid=100253533

Trials in Africa, Mexico show shot protects from the common diarrhea-causing disease.

WEDNESDAY, Jan. 27 (HealthDay News) -- Vaccinating infants against rotavirus could save the lives of millions of children in developing nations who would otherwise die from the diarrhea-causing disease, two new studies show.

A study conducted in Malawi and South Africa found vaccinations reduced the rate of severe, life-threatening rotavirus in infants by more than 61 percent.

A second study found deaths from diarrheal disease in Mexico fell by more than 66 percent in children 11 months and younger during the 2009 rotavirus season compared to 2003-2006. In 2006-2007, Mexico's Ministry of Health and other major health providers made the rotavirus vaccine part of its national vaccination programs.

"A disease that may be a nuisance in the U.S. can be a killer in a poorer country," said Dr. Kathleen Neuzil, senior author of the African study and a senior advisor for immunization at PATH, an international non-profit organization that seeks to bring affordable health care to all. "Death from diarrheal disease in general is the second-leading cause of death among kids in developing nations."

The studies are published in the Jan. 28 issue of the New England Journal of Medicine.

More than half a million children die each year from rotavirus infection, according to the World Health Organization (WHO). Nearly half of those deaths occur in sub-Saharan Africa. Though there are many gastrointestinal diseases that can cause life-threatening diarrhea, rotavirus is among the most common. Among children hospitalized for severe diarrhea, rotavirus is the culprit in about 40 percent of cases globally, according to background information in the study.

Rotavirus is also common in the United States, with most children having a bout of it before 3 years of age, Neuzil said. But few American children die, largely because of better access to medical care and treatments such as oral rehydration -- a mixture of water and electrolytes.

The U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices recommends that American children receive the rotavirus vaccine at 2, 4 and 6 months of age.

But before the WHO's Strategic Advisory Group of Experts on Immunization would recommend vaccinating children in developing nations, it wanted to see research that showed the vaccines would be effective in poorer nations, Neuzil said.

Both of the rotavirus vaccines available are live oral vaccine. Prior research on other live oral vaccines, including polio and cholera, has shown they don't work as well among very low-income populations. The reasons are unclear, but some suspect poorer nutrition or higher rates of the disease in those countries mean that children may already have some antibodies to the virus, perhaps through breast milk, so the vaccine may not fully "take," Neuzil said.

Prior to publication of the new studies, the results were shared with WHO, which has since recommended the rotavirus vaccine for infants in developing nations, with the first dose being given between 6 and 15 weeks of age.

The WHO's recommendation is critical, Neuzil said, not only for influencing health-policy decisions, but for starting the flow of aid and philanthropic dollars to pay for rotavirus vaccination programs.

In the study in Africa, researchers divided nearly 5,000 infants from Malawi and South Africa into three groups: one-third received three doses of the vaccine, one-third received two doses and one-third received a placebo. Researchers then followed-up with weekly home visits and took stool samples to confirm suspected rotavirus infections.

Children who had received either the three-dose or the two-dose regimen were 61 percent less likely to develop severe rotavirus infection. In Malawi, the effectiveness was 49 percent, compared to about 77 percent in South Africa.

In the study in Mexico, the effect was no less dramatic. During the 2009 rotavirus season, deaths among infants 11 months old and younger fell 66 percent.

In 2003-2006, about 1,793 children under age 5 died from diarrhea-related diseases each year in Mexico. In 2008, that dropped to 1,118, or nearly a 35 percent reduction. Among children between ages 1 and 2 years, deaths fell by about 29 percent in 2008, even though only 10 percent to 15 percent of the population was eligible for vaccination.

In an accompanying editorial, Dr. Mathuram Santosham, a professor of international health and pediatrics at Johns Hopkins University Bloomberg School of Public Health, said the studies provide powerful evidence for instituting rotavirus vaccination programs in developing nations throughout the world.

Malawi, South Africa and Mexico are countries with very different socio-economic patterns, Santosham said, with Malawi among the poorest in the world and South Africa relatively more affluent.

"The data from Mexico is representative of data that one would expect from Latin American countries," he said. "Therefore, I believe that these data can be extrapolated to the majority of developing countries."

Still, there are challenges. To protect children, WHO recommends infants receive the first dose between 6 and 15 weeks. In poorer nations, adherence to those guidelines can be spotty.

"Rotavirus vaccine is a very powerful tool to combat one of the leading causes of childhood deaths -- diarrhea," Santosham said. "The challenge now is to make sure that every poor child in the world has access to this life-saving intervention."

In a related study from the same journal, researchers cautioned that vaccinating immune-compromised children may make them sick. But the illness is likely to be mild even in children who are HIV-positive, Santosham said in his editorial.

More information

The World Health Organization has more on rotavirus vaccine.
SOURCES: Kathleen Neuzil, M.D., M.P.H., senior advisor for immunization, PATH, Seattle; Mathuram Santosham, M.D., M.P.H., professor, international health and pediatrics, Johns Hopkins University Bloomberg School of Public Health, Baltimore; Jan. 28, 2010, New England Journal of Medicine

Copyright (c) 2009 ScoutNews, LLC. All rights reserved.

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NEJM Volume 362:299-305 January 28, 2010 Number 4
Effect of Rotavirus Vaccination on Death from Childhood Diarrhea in Mexico
Vesta Richardson, M.D., Joselito Hernandez-Pichardo, M.D., Manjari Quintanar-Solares, M.D., Marcelino Esparza-Aguilar, M.D., Brian Johnson, B.S., Cesar Misael Gomez-Altamirano, M.D., Umesh Parashar, M.D., M.P.H., and Manish Patel, M.D.

ABSTRACT

Background A phased introduction of a monovalent rotavirus vaccine occurred in Mexico from February 2006 through May 2007. We assessed the effect of vaccination on deaths from diarrhea in Mexican children in 2008 and 2009.

Methods We obtained data on deaths from diarrhea, regardless of cause, from January 2003 through May 2009 in Mexican children under 5 years of age. We compared diarrhea-related mortality in 2008 and during the 2008 and 2009 rotavirus seasons with the mortality at baseline (2003--2006), before the introduction of the rotavirus vaccine. Vaccine coverage was estimated from administrative data.

Results By December 2007, an estimated 74% of children who were 11 months of age or younger had received one dose of rotavirus vaccine. In 2008, there were 1118 diarrhea-related deaths among children younger than 5 years of age, a reduction of 675 from the annual median of 1793 deaths during the 2003--2006 period. Diarrhea-related mortality fell from an annual median of 18.1 deaths per 100,000 children at baseline to 11.8 per 100,000 children in 2008 (rate reduction, 35%; 95% confidence interval [CI], 29 to 39; P<0.001). Among infants who were 11 months of age or younger, diarrhea-related mortality fell from 61.5 deaths per 100,000 children at baseline to 36.0 per 100,000 children in 2008 (rate reduction, 41%; 95% CI, 36 to 47; P<0.001). As compared with baseline, diarrhea-related mortality was 29% lower for children between the ages of 12 and 23 months, few of whom were age-eligible for vaccination. Mortality among unvaccinated children between the ages of 24 and 59 months was not significantly reduced. The reduction in the number of diarrhea-related deaths persisted through two full rotavirus seasons (2008 and 2009).

Conclusions After the introduction of a rotavirus vaccine, a significant decline in diarrhea-related deaths among Mexican children was observed, suggesting a potential benefit from rotavirus vaccination.

----------------------------------------------------
NEMJ Volume 362:289-298 January 28, 2010 Number 4
Effect of Human Rotavirus Vaccine on Severe Diarrhea in African Infants

Shabir A. Madhi, M.D., Nigel A. Cunliffe, M.B., Ch.B., Ph.D., Duncan Steele, Ph.D., Desire'e Witte, M.D., Mari Kirsten, M.D., Cheryl Louw, M.D., Bagrey Ngwira, M.D., John C. Victor, Ph.D., M.P.H., Paul H. Gillard, M.D., Brigitte B. Cheuvart, Ph.D., Htay H. Han, M.B., B.S., and Kathleen M. Neuzil, M.D., M.P.H.

ABSTRACT

Background Rotavirus is the most common cause of severe gastroenteritis among young children worldwide. Data are needed to assess the efficacy of the rotavirus vaccine in African children.

Methods We conducted a randomized, placebo-controlled, multicenter trial in South Africa (3166 infants; 64.1% of the total) and Malawi (1773 infants; 35.9% of the total) to evaluate the efficacy of a live, oral rotavirus vaccine in preventing severe rotavirus gastroenteritis. Healthy infants were randomly assigned in a 1:1:1 ratio to receive two doses of vaccine (in addition to one dose of placebo) or three doses of vaccine ― the pooled vaccine group ― or three doses of placebo at 6, 10, and 14 weeks of age. Episodes of gastroenteritis caused by wild-type rotavirus during the first year of life were assessed through active follow-up surveillance and were graded with the use of the Vesikari scale.

Results A total of 4939 infants were enrolled and randomly assigned to one of the three groups; 1647 infants received two doses of the vaccine, 1651 infants received three doses of the vaccine, and 1641 received placebo. Of the 4417 infants included in the per-protocol efficacy analysis, severe rotavirus gastroenteritis occurred in 4.9% of the infants in the placebo group and in 1.9% of those in the pooled vaccine group (vaccine efficacy, 61.2%; 95% confidence interval, 44.0 to 73.2). Vaccine efficacy was lower in Malawi than in South Africa (49.4% vs. 76.9%); however, the number of episodes of severe rotavirus gastroenteritis that were prevented was greater in Malawi than in South Africa (6.7 vs. 4.2 cases prevented per 100 infants vaccinated per year). Efficacy against all-cause severe gastroenteritis was 30.2%. At least one serious adverse event was reported in 9.7% of the infants in the pooled vaccine group and in 11.5% of the infants in the placebo group.

Conclusions Human rotavirus vaccine significantly reduced the incidence of severe rotavirus gastroenteritis among African infants during the first year of life. (ClinicalTrials.gov number, NCT00241644 [ClinicalTrials.gov] .)

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