Pathfinder
Editor, Senior Moderator
Swine flu models preparing Canada for pandemic
Canwest News Service: Tuesday, September 8, 2009 11:01 AM
Swine flu coverageThe hottest, most relevant, models in Canada these days are not necessarily the slim, leggy ladies that strut down the runways and adorn the pages of fashion magazines. The most important models that Canadians should know about are the mathematical ones being used to prepare the country for a more severe round of the swine flu this autumn and winter.
By now Canadians are likely used to seeing Health Minister Leona Aglukkaq, Chief Public Health Officer David Butler-Jones, and their provincial and local medical authorities on television and quoted in the newspapers. They are the public faces of the H1N1 pandemic, but behind the scenes, there are teams of mathematicians, physicists and other numerically inclined folks who are doing the groundwork that helps those officials make their policies.
Using mathematical models, these specialists are helping to answer critical questions. How many intensive care beds are going to be needed at the peak of the second wave? When is the second wave expected to reach its peak? Are social-distancing measures such as school closures useful? Will there be enough doses of the vaccine available before the second wave hits?
And perhaps the most important question of all ? how many Canadians are going to get sick?
Butler-Jones has refused to make predictions about how fierce, or how mild, the pandemic could become. He has consistently said that influenza viruses are notoriously unpredictable and, therefore, it's impossible to know the ultimate size of a pandemic.
While Butler-Jones has not been willing to be tied to numbers, Paul Smetanin and his team at Risk Analytica have offered plenty of predictions. The Toronto-based research firm anticipates that 25 to 30 per cent of Canadians will contract the swine flu virus by the end of the flu season, and that the peak of sickness will come in December or January.
"Get ready," was Smetanin's message to a gathering of health professionals and experts in Winnipeg last week. He spoke at a conference on the H1N1 pandemic that had a particular focus on managing severe cases of the disease. Most cases in Canada have been mild, but some people have required life-saving treatment in intensive care units and 72 people have died.
Risk Analytica has been doing work for Canada's National Microbiology Laboratory and for medical researchers across the country since early in the pandemic and will continue to be very busy through the fall as it collects more data and comes up with concrete numbers for different scenarios.
Smetanin, a native Australian who founded the company, presented the results of a study at the conference that was aimed at identifying the potential shortages of intensive care unit beds and the ventilators that have been crucial in pulling some patients through their bouts with the virus.
"We do expect the demand for ICU beds that are supported by ventilators to exceed supply and that's the big message," Smetanin said in an interview. That expectation is based on an attack rate of around 25 per cent of the population or higher, and assuming that about one-third of beds are taken up by non-flu patients.
The reason demand could outstrip supply is because of the length of stay in the ICU ward that patients are requiring. Using data from swine flu cases in Manitoba from May and June, Risk Analytica found that half of the 59 patients were on ventilators for more than two weeks and 10 per cent were hooked up to the machines for longer than 50 days. Almost everyone ? 93 per cent ? of patients in the ICU with swine flu needed a ventilator to help them breathe.
"Even though this pandemic virus does seem to be on the milder side of things, there are bottlenecks in the system and one of those key bottlenecks is ICU beds," said Smetanin. "If interventions aren't made in a timely matter, we're going to expect demand will exceed supply."
Those interventions include things like vaccination and hospitals creating more space in their ICUs, which are not taken into account in the model used to come up with the 25-per-cent attack-rate estimate. That estimate is assuming that the virus charts the same course as it has since the pandemic started in terms of its speed and that it doesn't mutate into a deadlier form.
Hospitals are being urged to prepare contingency plans in the event they are flooded with swine flu patients during the second wave.
While the estimates provided by Risk Analytica come with their share of limitations, the scenarios envisioned will still help hospitals figure out whether they can cope with a surge of ICU patients.
"Our job is to help them by giving them a head start, a heads up," Smetanin said.
A lot of behind-the-scenes work is also happening at the national level through the Canadian Consortium for Pandemic Preparedness Modelling. It consists of representatives from 23 public health agencies and academic institutions who collaborate on a daily basis.
The group is testing various scenarios and coming up with estimates that will be provided to the Public Health Agency of Canada, the group's chairman, Babak Pourbohloul, told Canwest News Service. The attack rate, the size of the pandemic, vaccine strategies, antiviral distribution and the impact of social-distancing techniques are all being analyzed using mathematical models.
"We provide these recommendations to the public health authorities and they take these recommendations into account to make their decisions," said Pourbohloul, who is the director of mathematical modelling for British Columbia's Centre for Disease Control.
He wouldn't share any of the estimates or recommendations just yet. The group is preparing a comprehensive report for the federal government that should be completed within the month.
http://news.globaltv.com/health/Swine+models+preparing+Canada+pandemic/1972028/story.html
Canwest News Service: Tuesday, September 8, 2009 11:01 AM
Swine flu coverageThe hottest, most relevant, models in Canada these days are not necessarily the slim, leggy ladies that strut down the runways and adorn the pages of fashion magazines. The most important models that Canadians should know about are the mathematical ones being used to prepare the country for a more severe round of the swine flu this autumn and winter.
By now Canadians are likely used to seeing Health Minister Leona Aglukkaq, Chief Public Health Officer David Butler-Jones, and their provincial and local medical authorities on television and quoted in the newspapers. They are the public faces of the H1N1 pandemic, but behind the scenes, there are teams of mathematicians, physicists and other numerically inclined folks who are doing the groundwork that helps those officials make their policies.
Using mathematical models, these specialists are helping to answer critical questions. How many intensive care beds are going to be needed at the peak of the second wave? When is the second wave expected to reach its peak? Are social-distancing measures such as school closures useful? Will there be enough doses of the vaccine available before the second wave hits?
And perhaps the most important question of all ? how many Canadians are going to get sick?
Butler-Jones has refused to make predictions about how fierce, or how mild, the pandemic could become. He has consistently said that influenza viruses are notoriously unpredictable and, therefore, it's impossible to know the ultimate size of a pandemic.
While Butler-Jones has not been willing to be tied to numbers, Paul Smetanin and his team at Risk Analytica have offered plenty of predictions. The Toronto-based research firm anticipates that 25 to 30 per cent of Canadians will contract the swine flu virus by the end of the flu season, and that the peak of sickness will come in December or January.
"Get ready," was Smetanin's message to a gathering of health professionals and experts in Winnipeg last week. He spoke at a conference on the H1N1 pandemic that had a particular focus on managing severe cases of the disease. Most cases in Canada have been mild, but some people have required life-saving treatment in intensive care units and 72 people have died.
Risk Analytica has been doing work for Canada's National Microbiology Laboratory and for medical researchers across the country since early in the pandemic and will continue to be very busy through the fall as it collects more data and comes up with concrete numbers for different scenarios.
Smetanin, a native Australian who founded the company, presented the results of a study at the conference that was aimed at identifying the potential shortages of intensive care unit beds and the ventilators that have been crucial in pulling some patients through their bouts with the virus.
"We do expect the demand for ICU beds that are supported by ventilators to exceed supply and that's the big message," Smetanin said in an interview. That expectation is based on an attack rate of around 25 per cent of the population or higher, and assuming that about one-third of beds are taken up by non-flu patients.
The reason demand could outstrip supply is because of the length of stay in the ICU ward that patients are requiring. Using data from swine flu cases in Manitoba from May and June, Risk Analytica found that half of the 59 patients were on ventilators for more than two weeks and 10 per cent were hooked up to the machines for longer than 50 days. Almost everyone ? 93 per cent ? of patients in the ICU with swine flu needed a ventilator to help them breathe.
"Even though this pandemic virus does seem to be on the milder side of things, there are bottlenecks in the system and one of those key bottlenecks is ICU beds," said Smetanin. "If interventions aren't made in a timely matter, we're going to expect demand will exceed supply."
Those interventions include things like vaccination and hospitals creating more space in their ICUs, which are not taken into account in the model used to come up with the 25-per-cent attack-rate estimate. That estimate is assuming that the virus charts the same course as it has since the pandemic started in terms of its speed and that it doesn't mutate into a deadlier form.
Hospitals are being urged to prepare contingency plans in the event they are flooded with swine flu patients during the second wave.
While the estimates provided by Risk Analytica come with their share of limitations, the scenarios envisioned will still help hospitals figure out whether they can cope with a surge of ICU patients.
"Our job is to help them by giving them a head start, a heads up," Smetanin said.
A lot of behind-the-scenes work is also happening at the national level through the Canadian Consortium for Pandemic Preparedness Modelling. It consists of representatives from 23 public health agencies and academic institutions who collaborate on a daily basis.
The group is testing various scenarios and coming up with estimates that will be provided to the Public Health Agency of Canada, the group's chairman, Babak Pourbohloul, told Canwest News Service. The attack rate, the size of the pandemic, vaccine strategies, antiviral distribution and the impact of social-distancing techniques are all being analyzed using mathematical models.
"We provide these recommendations to the public health authorities and they take these recommendations into account to make their decisions," said Pourbohloul, who is the director of mathematical modelling for British Columbia's Centre for Disease Control.
He wouldn't share any of the estimates or recommendations just yet. The group is preparing a comprehensive report for the federal government that should be completed within the month.
http://news.globaltv.com/health/Swine+models+preparing+Canada+pandemic/1972028/story.html