According to data provided on Google Flu Trends comparing to this year to 2003–2004 (a particularly severe year) the rate of estimated flu cases has climbed high and early. As for severity by state, this is what the map looked like in November last year:

Estimated USA flu severity map as at November 11, 2008 (Image: Google.)

And here’s what it looks like this year as of the end of October:

Estimated USA flu severity map as at October 30, 2009 (Image: Google.)

Finally, here’s a chart showing a comparison of Google estimated prevalence data and CDC prevalence data since the 2003–2004 season:

Yellow: CDC data. Blue: Google data. (Image: Google.)

How valid is this information (i.e. how much is it a reflection of actual rates of influenza infection)? It appears that Google’s flu prevalence estimate data based on search counts (a form of “syndromic surveillance”) are accurate predictors of reported rates of influenza in the United States. The Flu Trends About page (linked above) mentions the Nature study that Google undertook with a CDC researcher, and links to a free, Google-hosted version of the paper as a PDF file if you’re interested. This is further corroborated by the modest paper “More Diseases Tracked by Using Google Trends” that was published in the CDC web journal Emerging Infectious Diseases (Volume 15, Number 8–August 2009)^† though this is more of a research note than a detailed study.

I did find one interesting statement on this by the CDC, in answer to a direct question from a reporter. At a press briefing on May 5 Alice Park from Time posed the following to the CDC’s Richard Besser:

I just wanted to ask you about your opinion on some of the new flu tracking, surveillance service out there. I know that the CDC has worked with Google flu trends, for example, can you talk a little bit about how helpful that type of information is particularly now to get a better sense of the dynamics of the outbreak, you know, where it might be increasing or what the ebb and flow of it and is it getting worse, is it tapering off, can you comment a little bit about how useful those kind of methods are.

Besser replied:

In terms of our ability to detect emerging infectious disease, new infectious diseases, we’re constantly looking for what we call situational awareness. I mean what’s going on out in the communities. And we’re looking at you know, many, many different sources of information. The Google flu tracking information, there was a study done with Google in conjunction with CDC to look at can you use that information, can you use people going on the web to find information about flu as an indication of where flu is taking place? And the first year looking at that in terms of looking back, it was very helpful. The question is looking forward can you see that? As of two weeks ago, Google hits on flu on H1N1 are just off the charts. And so our website gets 8 million hits a day. So looking for a signal of increased activity on the web in a particular place isn’t very useful. But we’re open and are continually looking at various approaches to early detection because the sooner you can detect a problem, the sooner you can understand it and implement appropriate control measures.

Translation: I’m comfortable saying, with the benefit of hindsight, that Google Flu Trends in its first year of operation has done a pretty good job, but you are not going to hear me endorse it as a predictive tool for tracking H1N1. Or: it’s been shown to be valid, but we don’t yet know how reliable it is from year to year (or, for that matter, how much it might be influenced by special kinds of flu or fears about flu).

So, for what it’s worth, I’m going to go ahead and take it all with a grain of salt for now. I’ll say one thing though: it makes for some interesting graphics, and you have to admit that we’ve had a lot of graphs going down these past 18 months…

Related

The follow-up article for Time by Alice Park, “Is Google Any Help in Tracking an Epidemic?” published on May 6, 2009.

† Be warned: the CDC web site is even slower than your Toyota Yaris.

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• Google Flu Trends
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The author of the longest search query that resulted in a hit on my site reached a post entitled “Less is More.” It’s about razor blades…

We have found a close relationship between how many people search for flu-related topics and how many people actually have flu symptoms. Of course, not every person who searches for “flu” is actually sick, but a pattern emerges when all the flu-related search queries from each state and region are added together. We compared our query counts with data from a surveillance system managed by the U.S. Centers for Disease Control and Prevention (CDC) and discovered that some search queries tend to be popular exactly when flu season is happening. By counting how often we see these search queries, we can estimate how much flu is circulating in various regions of the United States.

They claim that this gives results two weeks earlier than existing methods. I wonder if you could predict an election with data like that…

Edited to add: What a difference a day makes. This screenshot shows that several states have moved from “low” to “moderate” flu activity based on data from the past 24 hours:

Compare this to Lydia’s screenshot which shows how the map looked yesterday. “Moderate” now includes Vermont, West Virginia, Alabama, Georgia and South Carolina, and Nevada has moved from “minimal” to “low.” Here comes that spike.

Related posts:

• Flu trends comparisons
• Skewed data
• What’s next for EveryBlock?

For example if, using Safari, you make Shortwave the first bookmark in your Bookmarks Bar, it is assigned the keyboard shortcut ⌘ + 1 (i.e. Apple key + 1). I defined a Shortwave commands file to include a search of Zero to One-Eighty (which you can query using “http://ztoe.net/?s=”), mapped to “z”. To search my site using Safari, I type “⌘ + 1,” then “z [search term]” then Return. Suh-weet. In Opera, ⌘ + 1 can be set to invoke the bookmarklet if you use Speed Dial, and in Camino, if you save the bookmarklet in the first folder in the Bookmark Bar and designate the folder as a Tab Group. (I don’t know if you can reassign ⌘ + [numeral] in Firefox.)

When you use a custom commands file, the dingus sends the search query plus the URL for your commands file to http://shortwaveapp.com, and then sends you to the destination address. For example:

http://shortwaveapp.com/?go&c=z%20elena&s=http://ztoe.net/misc/shortwave.txt

for the (custom) query “z elena.” It also sets a cookie whose content is the URL of your commands file.

Anyway, if you like using keyboard commands, this is a nice way to save keystrokes and mouse gestures, and (by providing your own bookmarklet) even give your visitors a customised way to search your site, if they are fanatical enough to tweak their browser for you.

Update: Firefox does not provide a way to customise it’s default keyboard shortcuts (for example to re-map ⌘ + 1 to invoke the bookmarklet instead of the first tab), but you can assign keywords to the bookmark by editing its Properties. For example, “sw” for Shortwave means I can invoke Shortwave using “⌘ + L,” then “sw + Return.” Not as nice as ⌘ + 1, but it’s a start.

Related posts:

• It’s the little things, Camino
• Using the keyboard for special characters