Washington (KRON/CNN) — Stanford University officials assured the public today that a vial potentially carrying live anthrax that was shipped to a campus laboratory last year has not threatened the school.

Stanford University on Thursday confirmed its medical school may be one of 18 locations that received live anthrax samples from the U.S. military.

The university said that “there is no threat to campus or public safety” from the shipment of a single vial it received in July. Stanford said the vial in question was not used by the university and was sent to the U.S. Centers for Disease Control for analysis. The university said it “has not received any reports of incidents or reactions” related to the shipment.

Four lab workers in the U.S. and as many as 22 overseas have been put in post-exposure treatment after the U.S. military inadvertently shipped live anthrax samples, some via FedEx, to labs in nine states, according to defense officials.

22 shipments of live anthrax made their way out of military facilities and into labs across the country, as well as to a U.S. base in South Korea. The shipments happened over a one-year period from March 2014 to March of this year.

The Pentagon said on Wednesday that a Maryland-based lab had alerted the Centers for Disease Control and Prevention that it had received live samples, prompting an across-the-board urgent review to see whether any other live anthrax has been shipped.

At least some of the live anthrax samples were sent via FedEx, according to a Defense Department official. The shipments, because they were thought to be dead, were shipped under less rigorous conditions than the live agent protocol.

Officials are concerned because samples left over at the lab in Dugway, Utah, where the samples originated, were tested and determined to contain live agent.

Science experts told the Defense Department there was no risk to the public from shipping in those containers.

Pentagon spokesman Col. Steve Warren said one sample was also sent to the Joint United States Forces Korea Portal and Integrated Threat Recognition Program at Osan Air Base in South Korea.

“The sample was destroyed in accordance with appropriate protocols,” Warren said.

As many as 22 people in a training laboratory were potentially exposed and were receiving treatment, according to a statement from the base, including five active duty Air Force members, 10 active duty Army members, three civilian officials and four contractors, a defense official said.

“All personnel were provided appropriate medical precautionary measures to include examinations, antibiotics and in some instances, vaccinations,” the statement from the base said. “None of the personnel have shown any signs of possible exposure.”

The facility was decontaminated afterward and the anthrax was destroyed.

Samples are supposed to be rendered dead before they are shipped under a routine research program. All military, government and commercial labs that may have received samples are now reviewing their inventory of anthrax.

The CDC is investigating in conjunction with the Defense Department and said they do not suspect any risk to the public.

“CDC is working in conjunction with state and federal partners to conduct an investigation with all the labs that received samples from the DOD,” Jason McDonald, a CDC spokesman said. “The ongoing investigation includes determining if the labs also received other live samples, epidemiologic consultation, worker safety review, laboratory analysis and handling of laboratory waste.”

A military spokesman confirmed there is no known public risk nor any illnesses reported.

“The DOD lab was working as part of a DOD effort to develop a field-based test to identify biological threats in the environment,” said Warren, the department spokesman. “Out of an abundance of caution, DOD has stopped the shipment of this material from its labs pending completion of the investigation.”

CNN’s Debra Goldschmidt and Jeremy Diamond contributed to this report.