What are we to make of the swine flu pandemic? The only thing I feel confident about is that it will be some time before we really know. A great deal of data and experience was gained in the year since the pandemic H1N1 took everyone by surprise but it will be a while before we can harvest all of it. Meanwhile I can say things were better than we thought they might be and certainly better than everyone's worst fears, but how much better -- better, how bad -- they were we just don't know. It was a very good year for people in my age category (over 65) as for reasons now becoming a bit clearer we were least susceptible. In ordinary flu years we are the most susceptible and we die in large numbers. This last year it was the young most at risk. The numbers of flu deaths overall don't tell the complete story, nor does the fact that many hospitals seemed able to cope. In Australia and New Zealand in the southern hemisphere who got the first full flu season with the virus, they almost didn't cope:

Intensive care units in New Zealand and Australia came close to turning seriously ill patients away during last year's swine flu pandemic, doctors say.

A year after the first cases of the virus were reported, researchers said it put 12 times the usual number of flu patients into intensive care in both countries last winter.

[snip]

Although the virus was a mild disease for most people, many with more serious symptoms needed critical care, Sydney-based intensive care specialist Ian Seppelt said.

"Most years, in that three-month period there are about 60 to 70 cases of viral pneumonitis in all [New Zealand and Australian] units."

Last year there were 856 cases - 119 in New Zealand - with 760 of those attributed to swine flu, he said.

[snip]

"If we had had any greater activity of that virus we would not have been able to offer that service [to everyone]."

Unlike normal flu seasons, it was predominantly younger people with no underlying symptoms who needed intensive care, Dr Seppelt said.

Wellington Hospital intensive care unit director Peter Hicks said he had "never seen anything like it before where we've had a disease that's so significantly impacted all the intensive care services across the two countries".

New Zealand hospitals had not had to turn people away from intensive care units but "it got close". (Kate Newton, The Dominion Post)

So instead of old people in intensive care it was a lot more young people. "A lot more" meaning an unprecedented number. When put that way, the swine flu episode doesn't sound quite so benign. Already analyses are showing that in terms of lives cut short prematurely, the 2009 pandemic was on the order of severity of the last pandemic in 1968 (full text of paper here). This is despite many medical advances in the interim.

How it will turn out in the fullness of time we don't know yet. And there is another flu season starting the southern hemisphere and we will get our usual one next fall and winter. What either will look like we also don't know. The betting is that pandemic H1N1 has replaced the previous seasonal H1N1 and will become the "new normal," i.e., the seasonally circulating H1 subtype. For some years yet a good proportion of the population still does not have natural immunity, although many acquired artificial immunity with the swine flu vaccine. What the impact will be we don't know, either.

Flu is like that.


http://scienceblogs.com/effectmeasur...u_down_und.php