ロタウイルスワクチンで大きな効果/米国医療事情

 2006年に認可されたロタウイルスワクチンは、流行開始を3ヶ月遅らせ、重症例を半分に減らし、大きな効果が出ていると政府が発表した。2008年初頭の発症は少なく、CDC連邦疾病管理・予防センターが15年前に監視を初めて以来のことである。非常に伝染性が強く乳幼児の激しい嘔吐下痢の主要な原因で、米国では毎年40万人が罹患し272,000人がER受診、70,000人が入院、20-60人が死亡する。全世界では約50万人が毎年死亡している。
 RotaTeqワクチンは、ロタウイルス感染の74%、重症感染の98%、入院の約96%を防止するとされている。
 最近15年のデータで、ロタウイルス流行は一般に11月半ばに始まるが、今回は2月末だった、検査件数は平年より37%少なく、陽性数は73.5%低かった。
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Rotavirus vaccine proves highly effective
http://www.latimes.com/news/science/la-sci-rotavirus26-2008jun26,0,2282421.story

画像Rotavirus
National Institutes of Health, International Committee on Taxonomy of Viruses

The highly contagious human rotavirus is the leading cause of severe vomiting and diarrhea in infants and young children around the world, killing 600,000 children annually.
It delayed the onset of the most recent season by three months, and the number of cases earlier this year was the lowest since tracking of the infection began.
By Thomas H. Maugh II, Los Angeles Times Staff Writer
5:22 PM PDT, June 25, 2008
A rotavirus vaccine approved in 2006 is having a significant impact in the United States, delaying the onset of the rotavirus season by three months and reducing its severity by about half, federal officials said today.

The incidence of rotavirus activity during the first months of 2008 was the lowest it has been since the federal Centers for Disease Control and Prevention began monitoring the illness 15 years ago, researchers from the agency reported in the CDC's Morbidity and Mortality Weekly Report.

The highly contagious virus is the leading cause of severe vomiting and diarrhea in infants and young children in the United States and around the world. Each year in this country, it causes more than 400,000 physician office visits, as many as 272,000 emergency-room visits, up to 70,000 hospitalizations and 20 to 60 deaths. Worldwide, about 500,000 children die from the infection each year.

The RotaTeq vaccine has been shown to prevent 74% of all rotavirus infections, 98% of severe infections and about 96% of hospitalizations. The CDC recommends that all infants receive their first dose of the vaccine by 12 weeks of age and all three required doses by 32 weeks.

No good data exist on the number of children who have been vaccinated, but studies at selected sites suggest that about half of 12-week-olds have received one shot and that about a third of 13-month-olds have received all three doses.

The decline in new cases appears "greater than expected based on the protective effects of the vaccine alone," Dr. Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases, said in a statement. She speculated that vaccination was helping to reduce the spread of the virus to unvaccinated individuals.

No agency tracks all cases of rotavirus in the United States. The new data come from the New Vaccine Surveillance Network, which tracks the virus in three typical counties, and the National Respiratory and Enteric Virus Surveillance System, a voluntary network of U.S. laboratories that test for the virus in samples provided by physicians.

For the last 15 years, the rotavirus season typically has begun in mid-November. This past winter, according to the report, it began in late February. The number of tests performed for rotavirus during the season was, on average, 37% lower than the number in previous years, and the number of positive tests was 78.5% lower.

In the three sentinel counties, the percentage of stool samples testing positive for rotavirus in children under 3 was 51% in 2006, 54% in 2007 and 6% in 2008.

thomas.maugh@latimes.com

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New Vaccine May Account for Less Severe Rotavirus Season
http://health.msn.com/health-topics/digestive-health/articlepage.aspx?cp-documentid=100205989
Hospital, doctor visits down sharply in many places, CDC reports
-- Scott Roberts
Hospital, doctor visits down sharply in many places, CDC reports.

WEDNESDAY, June 25 (HealthDay News) -- A new vaccine for rotavirus -- a leading cause of vomiting and diarrhea in infants and children -- may account for this year's less severe season, the U.S. Centers for Disease Control and Prevention said Wednesday.

The highly contagious virus is shed in the stools of infected people and is transmitted by contaminated hands and objects. Children can transmit the virus before and after they become sick with diarrhea.

The nation's leading cause of severe gastroenteritis in infants and young children, rotavirus typically is responsible for some 410,000 doctor visits, up to 270,000 trips to the emergency room, up to 70,000 hospitalizations, and as many as 60 deaths in the United States each year.

The numbers at many "surveillance centers" nationwide have been down sharply in the ongoing season. Lab tests for the virus are down 37 percent from average, and positive tests are 79 percent lower than usual, the CDC said in a prepared statement.

Also, rotavirus activity was delayed about three months from its typical start in November, and it peaked in April this year instead of the usual peak time of March, the agency said.

In 2006, Merck & Co.'s RotaTeq was introduced in the United States for routine vaccination of children at ages 2 months, 4 months, and 6 months.

"The changes appear to be greater than expected based on the protective effects of the vaccine alone," said Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases at the CDC. "It is also possible the current levels of vaccination may be helping to decrease the spread of rotavirus to unvaccinated individuals in the community."

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