Canada's Top Health Official says "the mortality rate from this [H1N1] is no worse than seasonal flu"

by Sharon Kirkey

Despite the recent surge in H1N1 deaths, the nation's chief public health officer says the pandemic virus appears no deadlier than regular seasonal influenza and that there could actually be substantially fewer flu deaths than normal this season.

Although H1N1 is disproportionately infecting more children and otherwise healthy young adults "the mortality rate from this [H1N1] is no worse than seasonal flu," Dr. David Butler-Jones said in an interview with Canwest News Service.

"The individual risk of severe disease or dying if you happen to get the flu is very similar today as it was back in June. It's just that we're starting to see a lot more people affected," he said.

"The fact that we haven't had more deaths and more people in [intensive-care units] I think is a testimony to people doing the right things to both prevent and reduce the severity of disease," Dr. Butler-Jones said. People are following public health advice to cough and sneeze into their sleeves, stay home if they're sick and get on anti-virals if symptoms are worsening, he said.

"When you do take this disease seriously, you can actually dramatically reduce the number of people with severe illness and death," Dr. Butler-Jones said. "So the usual 2,000 to 8,000 range [of flu-related deaths] that we see with seasonal flu, we might actually be able to reduce that substantially."

Experts said the rates of serious illness and death are far from the levels predicted for a novel pandemic virus and that, based on the information available up until now, H1N1 is not on track to causing disease and death on the scope or scale of the flu pandemics of the 20th century.

Given the delays in getting people vaccinated, that's a good thing, said Dr. John

Granton, president of the Canadian Critical Care Society.

"If this was a more deadly virus, we would be in big trouble."

Canada's national pandemic plan estimated a flu outbreak could cause 15% to 35% of the population to fall clinically sick, and force the hospitalizations of 34,000 to 138,000 people.

So far, an estimated 7% to 8% of the population has been infected between the first and second wave, Dr. Butler-Jones said.

While the number of hospitalizations jumped twofold in the week ending Nov. 7 compared with the previous week, to 1,324 from 661, according to the latest analysis from the Public Health Agency of Canada, there has been a drop in severe infections.

As well, the proportion of ICU admissions and deaths among those admitted to hospital with H1N1 is falling.

The number of new reported deaths were up fourfold in the same reporting period (35 versus eight).

But some say relying on deaths and hospitalizations can lead to what seems a sudden surge in population-wide sickness that does not paint a true picture.

It can take two to three weeks in many cases for people with influenza to get sick enough to end up in hospital or an intensive-care unit, and even longer for them to die, said Dr. Richard Schabas, a former chief medical officer of health for Ontario.

During the SARS outbreak in 2003, "people had the impression right through April of 2003 that the SARS outbreak was still roaring along, because they kept reporting deaths," Dr. Schabas said. "But what they didn't say was that these were people who got their SARS back in March, and it took them two, three, four, five weeks to die.

"It's the same thing with influenza. Most people with influenza don't die quickly. They die slowly. Continuing to report [deaths] as if it's a way of judging what the outbreak is doing is wrong." He said school absenteeism and emergency rooms visits are more timely indicators.

Estimating the death rate for swine flu is difficult, because the denominator -- how many people have been infected -- is missing. Canada, like most countries, stopped counting confirmed cases in July, and H1N1 causes mild symptoms in the majority of people it infects, so many people never see a doctor.

Reporting in this month's Harvard Health Letter, Harvard University researchers said data from the United States shows the death rate for H1N1 is one death for every 2,000 people who develop symptoms. The death rate for seasonal flu is about one death for every 1,000 to 2,000 infections.

During the 1957 flu pandemic, the death rate was elevated fourfold over regular seasonal flu, said University of Ottawa virologist Earl Brown.

In other words, for every person who dies of seasonal flu, the mortality rate was-four during the pandemic in 1957. "If you take 1968, where if you had one person dying per year, it went to two," Mr. Brown said.

"If we're looking here at 2009, one is going to, one? Less than one?" The data is incomplete, he said.


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