Public health officials say nearly 2,000 free swine flu vaccines at the Iowa State Fairgrounds ran out in less than four hours.

The Polk County Health Department offered both shots and mist version of the vaccine on Sunday as long as supplies lasted. Officials say the vaccine was gone by 1 p.m.

The shots were available to people in select groups including pregnant women, emergency workers and those from ages six months to 24 years.

Health officials say people in those groups are at a higher risk for getting the flu and experiencing severe complications such as pneumonia.

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