MEDFORD, Ore. — Officials in Jackson County are investigating after their counterparts in a California county asked passengers on a flight from Seattle to Medford last week to self-quarantine as a precaution due to possible exposure to the new coronavirus.

The original advisory came from public health officials in Humboldt County, California on Tuesday.

"Three recent flights may represent a possible exposure for COVID-19 infection, either because an individual on board has become a confirmed case or because a close contact whose test is pending was on board," the Humboldt County Joint Information Center said in a statement.

Officials listed three flights, only one of which came through Southern Oregon:

March 16: United Flight #5827 from Los Angeles Airport to Arcata

March 18: Delta Flight #4124 from Seattle to Medford, OR

March 18: United Flight #5555 from San Francisco Airport to Arcata

Health officials said that the actual exposure risk for most passengers would have been low, but all passengers are still advised to quarantine at home for 14 days, and contact a healthcare provider if they become ill with a fever, cough, or shortness of breath.

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After learning of the advisory, NewsWatch 12 reached out to Jackson County Public Health for more information. Officials said on Wednesday morning that they had not been notified of any potentially infected individuals on a flight into Medford. However, they said, such investigations are generally the purview of the CDC.

"When there is a confirmed case of COVID-19 on an airline, CDC will do the investigation, and will then share airline passenger’s contact information, that were close contacts, with the state public health department, who then provide that information to the local health department to investigate further and isolate/quarantine any individuals who may have been in close contact with the person," Jackson County said in a statement on Wednesday afternoon.

The Rogue Valley International-Medford Airport was likewise unaware of any precautions related to a Delta flight.

RELATED: Fourth case of coronavirus confirmed in Jackson County, public health officials say

Following Humboldt County's advisory, Jackson County reached out to the Oregon Health Authority to report the information. Eventually, the California State Department got in touch and confirmed the information about Delta Flight #4124.

"At this time, Jackson County Public Health does not have a list of who would be a close contact on this flight from the OHA," the County said, adding that the agency "continues to investigate this situation and is working to get flight information from the Oregon Health Authority in order to contact those that would be a close contact."

Regardless, Jackson County has joined Humboldt officials in asking those who were on the flight to self-quarantine for 14 days.

It is still unclear at this time why or how the flight to Medford was identified by Humboldt County officials, but never reached their local counterparts. NewsWatch 12 reached out to Humboldt County, which said the following:

"The Humboldt County Department of Health and Human Services - Public Health Branch made the appropriate notification to the California Department of Public Health who handles state-to-state notifications such as these."

Health officialsin both states are strongly recommending that people cancel all non-essential travel, which is included in both the California and Oregon stay-at-home orders.

"This travel not only increases your own risk of acquiring a COVID-19 infection, it increases the risk within our community," Humboldt County said.

On Tuesday, officials in Humboldt County identified a fifth case of COVID-19 in the county. Jackson County just announced its fourth case on Wednesday.

EDIT: This article has been updated as of 3/25 with responses from Jackson County Public Health and Airport Authority, as well as Humboldt County Joint Information Center.