Transcript for Coronavirus emergency on flight to London

very busy Friday night. We begin with the coronavirus emergency. The CDC revealing new measures being taken in the U.S. Today, we learned Americans in five major cities with flulike symptoms will also be tested for coronavirus. Passengers on a flight from the U.S. To the uk leaving from San Francisco were told by the pilot someone onboard may have coronavirus. One passenger said they were told to stay in their seats. It was never confirmed, but it was certainly alarming. China revealing the virus has sickened more than 1,700 medical workers, and 6 have died. Mass round-ups for people who may have the virus, not just sick people. Here's Maggie Rulli. Reporter: Tonight a scare on this united airlines jet landing in London. The captain announced that the person has a suspected case of coronavirus and that we were all to keep in our seats. Reporter: All 251 passengers were released but it's just the latest false alarm for already jittery travelers. Experts at home say the virus could last into next year. We want people to understand we likely will see more cases here in the United States. Reporter: The U.S. Announcing it will new test in five major cities. Individuals will also be tested for the China coronavirus. This will give us an early warning system. Reporter: In China a wartime campaign to stop the virus. After cracking down on patients violating quarantine rules. Now, home fever checks and a mass roundup of people who could have the virus. And tonight we're getting our first look at the toll on the front lines of this fight. China revealing more than 1,700 of its medical workers have contracted the virus and 6 have died. Doctors begging for more masks. Scientists showing how to make your own. In Japan, the first passengers allowed off that cruise ship for quarantine on land. 11 guests have chosen to be disembarked. Reporter: So far, more than 200 passengers have tested positive. We've been following John and Melanie Haering all week as he battled a high fever. Today he tested positive for the virus. I'm alone here in the room and I would rather be back on the cruise ship. We've been following his story for days. And we're all thinking about him and his wife. Maggie, we know the CDC has tried to get a team on the ground in China for weeks. You reported it looks like it could happen in the next few days. But back here at home, the CDC says they'll test at home in the U.S.? Reporter: Yeah, the secretary of health and human services says it is out of an abundance of caution. This is a precautionary measure only. Maggie, thank you. Next to the guilty verdict

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