Field of Science

The flu pandemic may be over, but it wasn’t a hoax

It’s over. Or it’s nearly over. The great influenza pandemic of 2009 – often called the swine flu – has peaked and declined, and it might be over until next year. Not only is it over, but in a remarkable demonstration of evolution at work, it may already have pushed the “old” seasonal flu out of the human population.

Don’t get me wrong: it could still come back in a second wave, as epidemiologists at the CDC and the WHO have been warning. They’re right, too: we just don’t know enough about this pandemic to be sure it’s over. Dr. Keiji Fukuda from the WHO said on Thursday:

“We see that activity is declining or has declined but we also continue to see in these areas a transmission of the virus, so it has not disappeared, and it is has not gone back to baseline. Based on the situation, our current assessment is that it remains too early to say that the pandemic is over. And it is unclear whether we will see in the northern hemisphere over the next few months during the winter and spring period another significant wave of activity.”
Further down in this post I’ll show why I think it’s over. I think this is great news, but not surprisingly the conspiracy theorists have to make some wild claims to grab attention while there’s still time. Let me address them first.

As reported in the Irish Times, the UK Daily Mail, and elsewhere, the WHO is being accused of inventing the pandemic in order to boost the profits of drug makers. Where did this conspiracy theory come from? Why, my old friend Wolfgang Wodarg, head of health at the Council of Europe:

“Council of Europe parliamentarian Wolfgang Wodarg called for an inquiry into what he called a `false pandemic' and the way it was handled at national and European levels, claiming pressure from pharmaceutical firms.” (Source: Irish Times)
Wodarg’s resolution calling for an investigation was just passed by the Council of Europe.

The last time I wrote about Wodarg, he was claiming that the flu vaccine causes cancer. As I wrote then, Wodard doesn’t know beans about the flu. Anyone who makes such unfounded, irresponsible claims deserved to be ignored, but because he’s a high-profile politician, the WHO had to respond. Dr. Fukuda, speaking for the WHO, said:

“The allegation by some, that the H1N1 pandemic is a fake is both scientifically wrong and historically inaccurate.”
As for the conspiracy claim, he said

“WHO has reached out to all parties who could help to reduce harm from the pandemic but we did take very great care to make sure that the advice received was not unduly influenced by commercial or non-public health interests.”
As for whether it was real, this map shows the deaths caused by pandemic flu this year:
You don’t have to be an epidemiologist to see that this has been a worldwide pandemic, with plenty of deaths. And keep in mind that these are just confirmed deaths due to flu; in many countries where surveillance is minimal or non-existent, we have no idea how many people were infected. It’s true that the number of deaths has been much lower than we feared, but back in the spring of 2009, no one knew how virulent this strain would be.

What I’d say to Wodarg (and what Dr. Fukuda might have wanted to say) is: Wodarg, you don’t know what you’re talking about. Your irresponsible claims are doing more harm than good. If you truly care about public health, then educate yourself before you speak out on the flu next time.

Now, why am I saying the pandemic is over? Well, in the U.S., the weekly surveillance reports from the CDC paint a very clear picture: the flu peaked in October and then declined rapidly, much like the seaonal flu does every year. Normally the peak occurs in January or February. Take a look at the latest data:
In the past three pandemics, in 1918, 1957, and 1968, our surveillance wasn’t nearly as good, so maybe there will be two flu seasons this winter. It could happen – we could get a second wave – but I’m putting down my $0.25 that it’s over.

Notice something else about this figure? The normal seasonal flu hasn’t been seen at all! The graph shows that virtually all cases are pandemic H1N1 flu. In contrast, here are the past 4 years of flu seasons: See what I mean? Just one peak each year, and the color-coding shows that the normal seasonal flu is a mixture of H3N1, an older H1N1 (not the new strain), and influenza B.

How about Europe? It’s fading there too: the European CDC report for January 15 says

“Sentinel physicians collected 735 respiratory specimens, of which 139 (19%) were positive for influenza virus. This proportion has now decreased for the seventh consecutive week. … Of the 15 486 influenza viruses detected by sentinel networks and subtyped since week 40/2009, 15 393 (99%) were the pandemic virus."
So in Europe too the pandemic is on the wane, and the normal seasonal flu strains are virtually absent. For those who follow the evolution of the flu, this is quite remarkable. It means that exposure to pandemic H1N1 provides protection against all three of the seasonal flu strains, and it suggests that a large proportion of the population has been exposed to pandemic flu – otherwise, more people would be getting sick with seasonal flu. Pandemic H1N1 has out-competed the old strains in less than a year – the blink of an eye in evolutionary time.

So I think it’s over. But get your H1N1 flu shot! I just got mine. Why? Well, there is a small chance of a second wave, and there’s no downside to the vaccine: after 60 million flu vaccinations in the U.S., there hasn’t been a single reported case of injury due to the vaccine. In addition, the flu might come early again next fall, just as it did this year, and a vaccination now will likely protect you through next season. And finally, don’t forget that vaccinating yourself is also protecting your family, friends, and community.

3 comments:

  1. I feel your picking only the big red circle graph to show deaths is misleading. Look down on the CDC's report to the P&I mortality section and you'll see that deaths from H1N1 are not significantly higher than average deaths from the seasonal flu, and are actually much lower than in the 2007-2008 flu season.
    While I grant the epidemic horizon was crossed for a while, I don't understand why so many people can't admit that there was an over-reaction to H1N1 from almost the very beginning.

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  2. You are correct that the number of deaths was no worse than for a typical seasonal flu. However, it was much worse for younger people and for pregnant women, who were disproportionately affected.

    I don't agree that was an over-reaction from the beginning. At the beginning - in April/May 2009 - we didn't know how deadly this would be. It turned out to be mild, so we got lucky. But without a rapid reaction, if it had been deadly, we'd have seen far higher numbers of deaths.

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  3. Update: other experts are agreeing with this prediction, nearly three weeks later - for example, see http://news.yahoo.com/s/ap/20100205/ap_on_he_me/us_med_swine_flu.

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