Tweet
Vaccinate all students, parents, health-care workers against H1N1: Study
Tom Spears
Published: Thursday, August 20, 2009OTTAWA -
The best way to contain a flu pandemic is to vaccinate all schoolchildren and their parents, but skip most adults, as schools are the main breeding ground for the bug, a major new study claims.
Vaccinating health-care workers helps too, says the study by Yale and Clemson universities.
"The biggest part of the story is you can stop the transmission chain very effectively by vaccinating schoolchildren," says Clemson mathematician Jan Medlock.
This challenges the view of the U.S. Centers for Disease Control and Prevention, which recommends vaccinating - in order of importance - pregnant women first, then caregivers or parents of infants, then health care workers, then babies, children and teens, then young adults, and finally adults from ages 25 to 65.
Canada hasn't yet issued its priorities, but has hinted at beginning with shots for people aged five to 40, and native communities.
Now Medlock and Alison Galvani of the Yale medical school says it's best to vaccinate those most likely to transmit viruses, rather than those at highest risk for complications.
They looked at two simple measures: How many illnesses, and how many deaths, can one prevent by vaccinating different age groups?
They also studied more complex measures such as total number of years of life lost across a population, and a pandemic's cost to the economy.Assuming there's a good vaccine, all those measures pointed to the same strategy for vaccinating.
"The best thing to do is to vaccinate schoolchildren - so, ages five to 19," as well as parents aged 30 to 39, Medlock said.
The study is published in the research journal Science.
The protective effect was so strong, he said, that vaccinating a mere 40 million Americans would contain the pandemic at the lowest possible level. That compares to more than 100 million doses of vaccine distributed in a normal flu year for the U.S, population.
And he said the findings apply whether a virus threatens mainly very old and young people (as in 1957) or mainly young adults (as in 1918-1919).
"This was striking," as the same result emerged for each simulation, "whether you count deaths, or infections, or costs - all of these things," he said.
"Really, the schoolchildren are the thing - going to school and mixing and transmitting among themselves are the important things to prevent if possible."
For elderly people, "the biggest part of our story is that you can actually protect them better, instead of vaccinating them directly . . . by vaccinating children - stopping the transmission in schools, and then from schoolchildren to their parents," he said.
Vaccines often don't work as well in the elderly, he said.
But there's a political dimension as well: Some parents would refuse to vaccinate their children.
The best way to contain a flu pandemic is to vaccinate all schoolchildren and their parents, but skip most adults, as schools are the main breeding ground for the bug, a major new study claims.
Newspapers across North American have been filled with letters from parents worried that this vaccine has been fast-tracked through safety tests.
As well, Medlock acknowledged, this flu isn't a terrible threat for children. "Their mortality is almost zero, and their symptoms are pretty mild in general. There's a consent question. We've seen all sorts of scares with additives to vaccine and so on."
At the University of Western Ontario, Dr. Marina Salvadori is a pediatric vaccination expert, and a member of the National Advisory Committee on Immunization.
It wouldn't be a simple measure to require mass vaccinations, she says. For instance, Texas faced a backlash from families when it tried to require human papillomavirus (HPV) vaccinations for girls.
It might be possible to allow families to abstain from vaccinations on medical, religious or philosophical grounds, as Ontario law allows for measles shots in schoolchildren, she said.
"You could make it the same" for flu, she said. But that would raise problems if flu showed up in a school with non-vaccinated children.
The report from the U.S. universities came on the heels of a Canadian study that said the H1N1 virus spreads at the same relatively slow rate as SARS and other influenza viruses.
That study says the 2009 pandemic virus appears to be less transmissible than the fall wave of the 1918 Spanish flu pandemic.
The transmissibility of the virus was determined by looking at data from the spread of the virus in Mexico City, said Babak Pourbohloul of the University of B.C. Centre for Disease Control.
"An estimation of this value at the early stage of an outbreak, specifically for an emerging infection, is very important, it's really key," said Pourbohloul - lead author of the study, published Tuesday in the online version of the academic journal Influenza and Other Respiratory Viruses.
"It will provide guidance to policymakers as to what intervention strategy they could use in order to effectively contain the infection."
However, he noted it's not known if the virus will mutate, allowing it to spread more easily.
"It's not easy to predict the timing" of mutation, he said. "It might happen in October, it might happen in November, it might not happen at all.
Tom Spears
Published: Thursday, August 20, 2009OTTAWA -
The best way to contain a flu pandemic is to vaccinate all schoolchildren and their parents, but skip most adults, as schools are the main breeding ground for the bug, a major new study claims.
Vaccinating health-care workers helps too, says the study by Yale and Clemson universities.
"The biggest part of the story is you can stop the transmission chain very effectively by vaccinating schoolchildren," says Clemson mathematician Jan Medlock.
This challenges the view of the U.S. Centers for Disease Control and Prevention, which recommends vaccinating - in order of importance - pregnant women first, then caregivers or parents of infants, then health care workers, then babies, children and teens, then young adults, and finally adults from ages 25 to 65.
Canada hasn't yet issued its priorities, but has hinted at beginning with shots for people aged five to 40, and native communities.
Now Medlock and Alison Galvani of the Yale medical school says it's best to vaccinate those most likely to transmit viruses, rather than those at highest risk for complications.
They looked at two simple measures: How many illnesses, and how many deaths, can one prevent by vaccinating different age groups?
They also studied more complex measures such as total number of years of life lost across a population, and a pandemic's cost to the economy.Assuming there's a good vaccine, all those measures pointed to the same strategy for vaccinating.
"The best thing to do is to vaccinate schoolchildren - so, ages five to 19," as well as parents aged 30 to 39, Medlock said.
The study is published in the research journal Science.
The protective effect was so strong, he said, that vaccinating a mere 40 million Americans would contain the pandemic at the lowest possible level. That compares to more than 100 million doses of vaccine distributed in a normal flu year for the U.S, population.
And he said the findings apply whether a virus threatens mainly very old and young people (as in 1957) or mainly young adults (as in 1918-1919).
"This was striking," as the same result emerged for each simulation, "whether you count deaths, or infections, or costs - all of these things," he said.
"Really, the schoolchildren are the thing - going to school and mixing and transmitting among themselves are the important things to prevent if possible."
For elderly people, "the biggest part of our story is that you can actually protect them better, instead of vaccinating them directly . . . by vaccinating children - stopping the transmission in schools, and then from schoolchildren to their parents," he said.
Vaccines often don't work as well in the elderly, he said.
But there's a political dimension as well: Some parents would refuse to vaccinate their children.
The best way to contain a flu pandemic is to vaccinate all schoolchildren and their parents, but skip most adults, as schools are the main breeding ground for the bug, a major new study claims.
Newspapers across North American have been filled with letters from parents worried that this vaccine has been fast-tracked through safety tests.
As well, Medlock acknowledged, this flu isn't a terrible threat for children. "Their mortality is almost zero, and their symptoms are pretty mild in general. There's a consent question. We've seen all sorts of scares with additives to vaccine and so on."
At the University of Western Ontario, Dr. Marina Salvadori is a pediatric vaccination expert, and a member of the National Advisory Committee on Immunization.
It wouldn't be a simple measure to require mass vaccinations, she says. For instance, Texas faced a backlash from families when it tried to require human papillomavirus (HPV) vaccinations for girls.
It might be possible to allow families to abstain from vaccinations on medical, religious or philosophical grounds, as Ontario law allows for measles shots in schoolchildren, she said.
"You could make it the same" for flu, she said. But that would raise problems if flu showed up in a school with non-vaccinated children.
The report from the U.S. universities came on the heels of a Canadian study that said the H1N1 virus spreads at the same relatively slow rate as SARS and other influenza viruses.
That study says the 2009 pandemic virus appears to be less transmissible than the fall wave of the 1918 Spanish flu pandemic.
The transmissibility of the virus was determined by looking at data from the spread of the virus in Mexico City, said Babak Pourbohloul of the University of B.C. Centre for Disease Control.
"An estimation of this value at the early stage of an outbreak, specifically for an emerging infection, is very important, it's really key," said Pourbohloul - lead author of the study, published Tuesday in the online version of the academic journal Influenza and Other Respiratory Viruses.
"It will provide guidance to policymakers as to what intervention strategy they could use in order to effectively contain the infection."
However, he noted it's not known if the virus will mutate, allowing it to spread more easily.
"It's not easy to predict the timing" of mutation, he said. "It might happen in October, it might happen in November, it might not happen at all.
