The CDC's summary report of the 2009 H1N1 pandemic outlines how tests were administered at the time. The virus was first detected in the US on April 15. The CDC informed the World Health Organization about initial cases April 18. A test to detect this strain of swine flu was developed by the CDC and cleared for use 10 days later, on April 28, and the CDC began shipping tests across the US and around the world on May 1.
Within the next four months, more than 1 million tests "were shipped to 120 domestic and 250 international laboratories in 140 countries," according to the CDC's report.
By May 18, 40 states were authorized to conduct their own 2009 H1N1 testing, with eight states having multiple laboratories that could process the tests, the report says.