An infected adult spent two full days — April 22 and 23 — hanging around Terminal 1 from 10 a.m. to 8 p.m. both times. The person only had one dose of the MMR vaccine, which protects about 93% of people but clearly wasn’t enough here. A few days later they got fever and the classic rash, got tested, confirmed measles, and went straight into isolation at home.

Then, just a few days after that, a second adult in the same Illinois county showed up at a hospital with measles symptoms on April 28. Staff caught it fast and isolated them right away. They’re still don’t know if the two cases are connected or what the second person’s vaccine status is, but the timing and location definitely raise eyebrows.

Because O’Hare is such a huge hub, thousands of people could have been exposed and are now scattered all over the country and the world. Measles spreads crazy easily through the air and can hang in the air for two hours after the sick person leaves, so terminals, food courts, security lines — all perfect for it.

Health officials are telling anyone who was in Terminal 1 during those hours to watch for symptoms (fever, cough, runny nose, red eyes, then the rash) for up to 21 days later. If you think you were there, call your doctor first instead of just walking in, and definitely check your vaccine records. Two doses of MMR give 97% protection, which is why they keep pushing everyone to be fully vaccinated.

Right now they’re doing contact tracing and watching for more cases. So far these are the only two confirmed in this cluster, but everyone’s on high alert because measles can take off fast if it hits an under-vaccinated pocket.