NEW YORK (June 21, 2012)--A study of bird flu that was once considered too risky to publish has finally been released, the second of two papers whose publication was delayed by concerns that the information could help terrorists create bioweapons.

People get bird flu from infected poultry but those infections are rare.

The two papers suggest the virus could easily spread between people instead if it gained particular genetic mutations, which the papers identify.

Scientists have long worried that person-to-person spread could cause a deadly pandemic.

Last year, federal regulators asked the researchers not to publish details of the work, but in April, they approved publishing revised versions of both papers, saying the benefits of sharing the information outweighed the risk.

The second paper was published Thursday in the journal Science.