ATLANTA (AP) – At least 99 percent of the killer flu samples mistakenly sent to laboratories around the world by a medical supply house have been recovered and destroyed, and there have been no infections, the government said Thursday.

Health officials have been scrambling since it was learned nearly two weeks ago that a dangerous strain was sent to 3,757 labs in the United States and 18 countries.

Only a “few stragglers” – about three dozen labs – have not yet destroyed the samples, and health officials are working feverishly to make sure they do so, said Dr. Julie Gerberding, director of the Centers for Disease Control and Prevention.

The government is investigating why and how Meridian Bioscience Inc. of Newton, Ohio, sent out the flu samples.

The vials were included in test kits sent to laboratories to gauge their proficiency at detecting various strains of the flu.

The Asian flu strain killed between 1 million and 4 million people in a 1957 outbreak.

The strain had not been included in flu vaccines since 1968, and anyone born after that date has little or no immunity to it.

“We don’t know whether the strain involved in the test kits could infect people or not, so we had to assume it could,” Gerberding said.