There are 300 non-government research labs registered to work with deadly germs like the Spanish flu, which killed millions of people worldwide. The Centers for Disease Control and Prevention will consider requests for samples from those labs "on a case-by-case basis," CDC spokesman Von Roebuck said Wednesday.

Dangerous biological agents are routinely shipped through commercial carriers like FedEx or DHL, following government packaging, safety and security guidelines.

Last month, U.S. scientists announced they had created — from scratch — the 1918 virus. It was the first time an infectious agent behind a historic global epidemic had ever been reconstructed.

Researchers said they believed it would help them develop defenses against the threat of a future pandemic evolving from bird flu, which was found to have similar characteristics as the 1918 virus.

About 10 vials of virus were created, each containing about 10 million infectious virus particles. CDC officials said at the time the particles would be stored at a CDC facility in Atlanta, and that there were no plans to send samples off campus.

But that statement did not mean there was a policy against sending samples elsewhere, Roebuck said.

The agency's decision to consider shipping the virus outside Atlanta was first reported in the latest issue of the journal Nature. Some critics of the recreation of the virus were not pleased to learn of plans to ship the germ.

"Obviously, that contradicts what most people were led to believe when the results of the 1918 experiments were published," said Edward Hammond, director of the Sunshine Project, an Austin, Texas-based organization that advocates more control of biological weapons and biotechnology.

In addition to creating the virus, the scientists said they would place the gene-sequencing information from the new research in GenBank, a public database operated by the National Institutes of Health.

GenBank will allow some research groups to build their own virus, rather than seek samples of what the CDC had created.

"But that would be a lot of work. Wasted, duplicative work, if they (the CDC) have already made it," said Dr. Diane Griffin, chair of molecular microbiology and immunology at Johns Hopkins University's Bloomberg School of Public Health.

It's impractical to expect every influenza researcher who could learn from the 1918 virus to travel to Atlanta, said Michael Osterholm of the University of Minnesota School of Public Health.

"There's very limited lab space there," said Osterholm, director of Minnesota's Center for Infectious Disease Research & Policy.

The CDC currently has no pending requests for the virus, Roebuck said. It's unlikely many requests would come in right away, Osterholm noted.

The government requires researchers who work with such agents to use highly secure labs that meet strict training and equipment requirements. About 300 labs are registered for handling such agents, and all are located in the United States, Roebuck said.

"This (virus) is not going to go willy nilly to anyone who wants it," he said.