Swine flu — officially a pandemic

I posted about swine flu a while back, before we really knew anything. Since the WHO just moved to stage 6 and declared it a pandemic, causing my RSS feeds to explode with yet more newshype, it seems like a good time for an update.

Stage 6 doesn’t mean the disease is getting more serious/deadly or anything like that, just that it’s now indisputably widespread. SARS, for example, was a very deadly disease but it wasn’t a pandemic since it was contained in a relatively few locations and we could track the chains of transmission. We can’t do that for H1N1 right now — it’s out there in the community, and some people who have it have no clear connection to anyone else who has it. Severity can be one indicator of a pandemic (the WHO seems to be waffling about that a bit) but in general it’s just an indication of the extent of a disease’s spread and not its lethality. Take home message: declaration of stage 6 is not in itself a reason to head to the back woods with two tonnes of tinned beans and a shotgun.

The BBC has a sensible quote from flu expert Professor John Oxford:

“It is global and fulfilling the requirements of a pandemic but I don’t think anyone should worry because nothing drastic has happened between yesterday and today.”

Initially it was looking like H1N1 might be up to 6% lethal. Fortunately, so far the numbers indicate that it’s much, much less lethal than that. Today the numbers I’m seeing show 27,737 official cases of swine flu, including 141 deaths. That puts the death rate at roughly 0.5%. To put those 141 deaths in context it helps to remember that normal seasonal flu, from what we can tell, kills upwards of a quarter of a million people every year and gets much less fanfare (not, of course, that it makes the 141 H1N1 deaths any less tragic). The Pump Handle blog puts it well:

The influenza virus kills people all the time. We don’t know exactly how many but we know that many people die of various immediate and underlying causes that wouldn’t have died at that time if they hadn’t become infected with the influenza virus in the period prior to their demise. Influenza is like heart disease or diabetes or cigarette smoking: a major cause of mortality that we have become used to. As long as it is described in terms of familiar seasonal influenza the public is all right with it — until they get a good dose of this really miserable illness.

It’s worth repeating that flu of any kind is deeply, deeply miserable, even if it’s technically “mild”. “Mild” in this context means “not terribly dangerous” and “not in much need of medical assistance,” not “a bit of a sniffle, continue with your everyday activities”. H1N1 sounds pretty similar to normal seasonal flu except it seems to involve some vomiting, which isn’t typically a flu symptom. So you have your usual week or two of flu-related extreme exhaustion, cough, bone aches, fever, chills, headache and all the rest PLUS hurling. Lovely!

But remember those 27,737 official cases were the folks who were sick enough to need to see a doctor or go to Emerg. There are probably a large number of cases out there where people just felt ill and stayed home without visiting a doctor, so their cases didn’t get counted in the numbers. This means the true death rate is probably rather lower than 0.5%. New York, for example, thinks they may have had about a half-million unofficial cases and only 12 deaths, which some mental math estimates is about 1 in 40,000. Canada has had 2,446 H1N1 cases and three deaths, so about 1 in 800 or 0.12%. Take home message: It’s always a good idea to have your affairs in order, but this flu is not all that likely to kill you, assuming you’re reasonably healthy to begin with and if you get medical help if you need it.

The CDC in the US put out quite a good press release detailing what H1N1 symptoms do indicate more serious problems:

In children, signs that need urgent medical attention include fast breathing or trouble breathing; blueish or gray skin color; not drinking enough fluids; severe, persistent vomiting; not waking up or not interacting.; being so irritable that the child doesn’t want to be held; and flu-like symptoms improve, but then return later with a fever and a worse cough. Those are warning signs we physicians think about all the time, with respiratory infections. And they’re good to have in mind with this new influenza-like illness caused by the novel H1N1 strain. Just good things for parents to have in the back of their mind.

In adults, we look at another set of warning signs that suggest the need for urgent medical attention: difficulty breathing or shortness of breath; pain or pressure in the chest or abdomen; sudden dizziness, confusion, persistent or severe vomiting that doesn’t go away; and flu-like symptoms that improve, but then come back again with a fever or worsening of cough.

Of course, if you do have some sort of medical condition already (asthma and other respiratory problems seem high on the list), it’s a good idea to consult your doctor as soon as you might think you have the flu. Call first so they’ll be able to isolate you appropriately. You don’t want to be sitting around a waiting room or Emergency department shedding virus all over everybody.

So yes. Flu is no fun and at this point there’s a pretty decent chance lots of us will catch it, but it’s not an OMG WE’RE ALL GONNA DIE, DIE, DIE! thing. Wash your hands a lot. Maybe buy some extra freezies and clear fluids — you’ll get through them eventually and if you do get sick you won’t want to go out shopping (nor does the rest of the world want your germs). Maybe ride your bike to work instead of taking the subway (see, I can work a plug for bike commuting into any topic!). But don’t panic — this bug is not the apocalypse; we don’t have to hand the world over to the cockroaches just yet.