Microsoft is not the only one with some new offerings in the way of health search today. Google has added a slew of new cities to its Flu Trends product. The move is timed well, as the company acknowledges that it is National Influenza Vaccination Week.

"Since the strain of influenza that is active (H1N1) is novel, no one knows exactly what will happen next. However, the CDC is warning that one possibility is a second spike of flu activity, which is what occurred in 1957 when another novel strain of influenza spread in the United States," says Google Software Engineer Matt Mohebbi. "We’ve been chatting with public health officials about new ways we can help people understand the spread of flu during this unusual time and today we’re excited to bring city level flu estimates to 121 cities in the United States."

"By tracking the popularity of certain Google search queries, we’re able to estimate the level of flu in near real-time," says Mohebbi. "Google Flu Trends is updated daily and may provide early detection of flu activity, since traditional flu surveillance systems often take days or weeks to collect and release data."

The city-level estimates provided by Google Flu Trends are considered "experimental" because they have not been validated with official data, but Google says that the estimates are made in a similar manner to its national estimates, which have been validated.

A complete list of the cities Google tracks can be found here.

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The flu is a hot topic right now, unfortunately. A lot of people have it, have had it recently, or will get it soon. Flu shots are all over the news – Who gets them first? How many are available? Should you even get one? These are all questions circulating through the news media.

Last year Google launched its Flu Trends tool in the United States, and has now taken the opportunity to expand it into 16 additional countries. The site is also now available in 37 different languages.

"By tracking the popularity of certain Google search queries, we are able to estimate the level of flu, in near real-time," says Google. "While some traditional flu surveillance systems may take days or weeks to collect and release data, Google search queries can be counted immediately. Google Flu Trends provides an additional surveillance tool that may help public health officials and the public make more informed decisions about preparing for the flu season."

"In the past year, we’ve expanded our coverage to include Mexico, New Zealand and Australia and have continued to see a good correspondence between our estimates and official flu activity data. In fact, our analysis of last season shows that Google Flu Trends had a close 0.92 correlation with official U.S. flu data," the company adds.

Countries where Flu Trends is now available include: Australia, Austria, Belgium, Bulgaria, Canada, France, Germany, Hungary, Japan, Mexico, the Netherlands, New Zealand, Norway, Poland, Russia, Spain, Sweden, Switzerland, Ukraine, and the US.