Tuesday, May 21st, 2013
Four germs have been identified by a new study as the causes of severe–and often fatal–diarrhea in infants and children worldwide, leading researchers to call for better dissemination of the vaccine against rotavirus, one of the four germs. The New York Times has more:
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Diarrhea is a major killer of children, with an estimated 800,000 deaths each year; it has many causes, and doctors want to focus on the most common ones to bring death rates down.
The study, financed by the Bill and Melinda Gates Foundation and published by The Lancet, found that the most common causes were rotavirus; a protozoan called Cryptosporidium; and two bacteria, Shigella and a toxin-producing strain of E. coli. In some areas, other pathogens, including the bacteria that causes cholera, were also important.
The study followed more than 9,000 children with diarrhea seen at clinics in Bangladesh, Gambia, India, Kenya, Mali, Mozambique and Pakistan, and, for comparison, more than 13,000 children without the disease. The children with diarrhea were more likely to have stunted growth and eight times as likely to die during a two-month follow-up period.
Diarrhea seemed to be linked to chronic malnutrition, which causes gut inflammation that can make it harder to digest food.
The prominent role of Cryptosporidium came as a surprise to the authors; it had been best known as a killer of adults whose immune systems were suppressed by AIDS.
In an editorial accompanying the study, other experts said rotavirus vaccine could save many lives.
Friday, April 5th, 2013
The varicella vaccine, which immunizes against the virus that causes chickenpox, has been found in a new study published online in the journal Pediatrics to be highly effective after one dose, and even moreso after two doses. More from The New York Times:
Before 1995, when the varicella vaccine came into widespread use, chickenpox affected about 90 percent of the population, leading to thousands of hospitalizations and about 100 deaths a year.
“Now a very safe vaccine will totally prevent it from happening,” said the lead author, Dr. Roger Baxter, co-director of the Kaiser Permanente Vaccine Study Center in Oakland, Calif.
Between June and November 1995, researchers began studying 7,585 children vaccinated between the ages of 1 and 2. They interviewed their parents every six months, asking about the occurrence of both chickenpox and shingles, the painful rash that can occur after recovery from chickenpox. In June 2006, a second vaccine dose was recommended, and the researchers followed those cases through the end of the study in 2009.
The analysis, published online in Pediatrics, found 1,505 cases of chickenpox, all except 30 of which were mild or moderate, involving less than 300 lesions. There were no cases among children who received a second dose.
Image: Infant getting vaccine, via Shutterstock
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Friday, March 29th, 2013
Another study, this one from the Centers for Disease Control and Prevention, has found no connection between vaccines and autism spectrum disorders (ASD). This is the latest in a series of research studies that followed a highly controversial 1998 report in the British journal The Lancet, which alleged a causal link between vaccines and ASD. That article was recanted in 2010. More on the new CDC study from NBC News:
In the first six months of life, children receive as many as 19 vaccine doses of six different vaccines, and by the time they are 6 years old, a total of 25 doses from 10 vaccines.
In a 2011 survey, about a third of parents expressed concerns that their child received too many vaccines before age 2, and too many vaccines on a single day.
Previous studies have found no link between the number of vaccines a child receives and their risk of several neurological conditions (though these studies did not specifically consider autism).
The new study went a step further by looking at the link between a child’s total exposure to antigens — the proteins in vaccines that stimulate the body’s immune system — and his or her risk of autism.
The researchers looked at total antigen exposure rather than the total number of vaccines kids received because, at the root of parents’ concerns is the idea that “somehow they provide too much immunological stimulation, more so than a young child’s immune system can handle,” said study researcher Dr. Frank DeStefano, of the Centers for Disease Control and Prevention. (The sheer number of vaccines would not be as good a measure of immunological response because vaccines contain different numbers of antigens, and some protect against more than one disease, DeStefano said.)
DeStefano and colleagues analyzed information from about 250 children with autism and 750 children without autism, born between 1994 and 1999.
Children with autism were exposed to about same total number of antigens as children without autism at ages 3 months, 7 months and 2 years. There was also no difference between the two groups in terms of the total number of antigens they were exposed to on a single day.
“Parental concerns that their children are receiving too many vaccines in the first two years of life, or too many vaccines at a single doctor visit are not supported in terms of an increased risk of autism,” the researchers write in the March 29 issue of the Journal of Pediatrics.
Previous CDC research has shown that most U.S. children–as high as 95 percent–still receive vaccines on the recommended schedule. In 2011, a study from the Institutes of Medicine also found no causal link between autism and vaccines.
Image: Baby receiving vaccine, via Shutterstock
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Thursday, January 24th, 2013
Nearly half of U.S. children receive recommended vaccines on a delayed schedule, a new report conducted by Kaiser Permanente has found. Further, researchers say that the rising number of children who skip the vaccines altogether could reintroduce some long-eliminated diseases back into the mainstream. More from Reuters:
“What we’re worried about is if (undervaccination) becomes more and more common, is it possible this places children at an increased risk of vaccine-preventable diseases?” said study leader Jason Glanz, with Kaiser Permanente Colorado in Denver.
“It’s possible that some of these diseases that we worked so hard to eliminate (could) come back.”
Glanz and his colleagues analyzed data from eight managed care organizations, including immunization records for about 323,000 children.
During the study period, the number of children who were late on at least one vaccine – including their measles, mumps and rubella (MMR) and diphtheria, tetanus and pertussis (DTaP) shots – rose from 42 percent to more than 54 percent.
Babies born towards the end of the study were late on their vaccines for more days, on average, than those born earlier.
“When that happens, it can create this critical mass of susceptible individuals,” said Saad Omer, from the Emory Vaccine Center in Atlanta, who wasn’t involved in the new study.
Just over one in eight children went undervaccinated due to parents’ choices. For the rest, it wasn’t clear why they were late getting their shots. Some could have bounced in and out of insurance coverage, Glanz suggested, or were sick during their well-child visits, so doctors postponed vaccines.
The report comes on the heels of new data from the Institute of Medicine saying that the recommended infant vaccine schedule is safe for children.
Image: Baby vaccine, via Shutterstock
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Thursday, January 17th, 2013
The crowded schedule of vaccines recommended for babies, sometimes requiring five shots in a single doctor’s visit, is safe, a new report from the Institute of Medicine has found. The report, researchers say, should comfort parents who worry that the repeat shots could overload babies’ fragile immune systems. More from MSNBC.com:
“Our committee found no evidence that the childhood immunization schedule is not safe,” Ada Sue Hinshaw, Ph.D, dean of the graduate school of nursing at the Uniformed Services University of the Health Sciences and chair of the committee, told reporters in a conference call.
The Institute, one of the independent National Academies of Science, was asked to look at studies involving not the vaccines themselves, which have been shown numerous times to be safe, but at the schedule for their delivery.
Babies are vaccinated against diphtheria and tetanus, whooping cough and measles, chickenpox and bugs that cause meningitis, pneumonia and diarrhea. Some shots have to be given multiple times over a period of months to fully protect a child, and the schedule is based on when a child becomes vulnerable to infections, as well as when their immune system is developed enough to respond the vaccines.
“A number of concerned parents say the schedule is too ‘crowded’ and have requested flexibility, such as delaying one or more immunizations or having fewer shots per visit,” the committee says in its report.
“Some parents have rejected the vaccines outright, arguing that the potential harm of their child suffering a side effect from the vaccine outweighs the well-documented benefits of immunizations preventing serious disease. Other parents delay or decline immunizations due to worries that family history, the child’s premature birth, or an underlying medical condition may make them more vulnerable to complications. Some simply distrust the federal government’s decisions about the safety and benefits of childhood immunizations.”
And delaying or refusing vaccination can cause harm — not only to the children who are not fully vaccinated, but to those around them, the committee noted. “States with policies that make it easy to exempt children from immunizations were associated with a 90 percent higher incidence of whooping cough in 2011,” the report says.
Image: Baby getting vaccine, via Shutterstock
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