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CHICAGO — A Chicago man in his 60s has been diagnosed with the seventh confirmed case of COVID-19 in Illinois, city and state officials said Sunday.

Chicago Department of Public Health Commissioner Dr. Allison Arwady said the man is currently hospitalized in serious condition. However, unlike previous cases in the state, Arwady said it doesn’t appear to be connected to travel.

“Though this may be the first case of community transmission in Chicago, it does not mean that widespread transmission of COVID-19 is happening here,” Arwady said.

As health agencies search for potential sources of infection, officials with Amtrak said Sunday night a passenger who took the 303 train from Chicago to St. Louis on March 4 later tested positive for COVID-19.

Officials say she studied abroad in Europe, flew to O’Hare on March 3, stayed overnight with a friend and then took the train to Missouri the next day.

Amtrak is now in the process of notifying passengers and employees who may have been on the 303 train, and have taken the train out of service to sanitize it. They also plan on sanitizing the Chicago and St. Louis stations.

Earlier in the day Sunday, health officials confirmed Illinois’ seventh COVID-19 case was discovered after a Chicago man sought medical care for flu-like systems.

Arwady credits a surveillance system in place in Chicago and Illinois with discovering it. As part of this system, people who seek medical attention at participating hospitals with flu-like symptoms but test negative for flu, or are hospitalized with respiratory issues, can be flagged and tested for COVID-19 by the Illinois Department of Public Health.

“As we enhance our surveillance efforts and begin testing more people, we do expect to see additional cases,” Arwady said.

While people who are older or have compromised immune systems should avoid traveling and large gatherings, Arwady said, there’s no recommendation for people in the Chicago area to cancel mass gatherings or public events at this time.

WATCH ABOVE: CDPH Commissioner Dr. Allison Arwady and IDPH Director Dr. Ngozi Ezike speak after Illinois’ 7th case of COVID-19 is found in Chicago

As the state expands its surveillance efforts, IDPH Director Dr. Ngozi Ezike said they are looking into public-private partnerships with companies that are developing additional tests. Ezike said there are other possible cases of COVID-19 in Illinois, but the department is currently testing them.

This is the third case detected in Chicago, and comes shortly after a woman who works as a special education assistant at Vaughn High School tested positive for COVID-19. Arwady said there’s no evidence the latest case is connected.

“The potential for more community transmission is absolutely there, and we’re prepared for this and we want to make sure everyone is prepared in case we do see that in the future,” Arwady said.

Since the main transmission of COVID-19 is through droplets when people cough and sneeze, investigators are most concerned with those that have had close contact with a confirmed case, which is considered 10 minutes of face-to-face contact.

As such, measures such as washing hands, keeping distance between people and covering their mouth when they cough or sneeze can help keep the virus from spreading.

“It signals how important it is, again, for anyone who has flu-like symptoms — fever, cough respiratory illness — to stay home from school and work unless needing to seek medical attention,” Arwady said.

The other previous coronavirus cases in Illinois include a college student in his 20’s who returned from Italy, who is recovering at home in good condition. Of two couples where both husbands and wives were infected, the first two recovered and the second pair is in home isolation doing well.

Both officials asked residents to plan ahead and prepare for contingency plans, should parents or their children need to stay home for an extended period of time, and to reconsider any large public gatherings.