A dog-flu epidemic plaguing Chicago has been caused by a strain of the virus not previously seen in North America, scientists at Cornell University and the University of Wisconsin announced Sunday.

There is no evidence it can be transmitted to humans, officials said. But it’s not known if the current vaccine provides any protection from the new virus, according to a Cornell University press release.

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Donna Alexander, the administrator of the Cook County Department of Animal and Rabies Control, said Chicago pet owners should still have their animals vaccinated.

“The vaccine may not be completely protective against this strain,” Alexander said. “But it does impart enough of an immunity that it may protect the animal’s life. It may make the difference between it being a fatality and a severe hacking cough that the animal can withstand.”

While the outbreak that has afflicted more than 1,000 dogs in Chicago had been attributed to the H3N8 strain of the virus, researchers at Cornell said results from additional tests show the outbreak has been caused by the H3N2 virus in wide circulation in southern Chinese and South Korean dog populations.

Both strains can cause high fever, loss of appetite, coughing, nasal discharge and lethargy — though symptoms may be more severe in cases caused by the H3N2 virus, Cornell officials said.

H3N2 also has caused infection and respiratory illness in cats, according to Cornell.

Contributing: Becky Schlikerman