Oh ok. Marek's disease is probably what you were thinking. It's best to avoid bringing disease home at all costs because it's almost impossible to get rid of it. Hopefully this round goes better for you.Honest to God, no idea. I haven't been on since maybe 2018? We lost our flock at the end of 2019 - the had all passed, and we did not start a new one as we had just had our daughter at the time and we weren't sure if it was the disease that you have to wait like 10 years. My husband was starting a new coop this year so we could start a new flock.
Just remember that ventilation is a must even in the cold weather.