Is acute bronchitis contagious?

Yes: Acute bronchitis is currently considered to be caused mostly by viruses, which are quite contagious. It can be transmitted in the air, by coughing, and by contact with the sick person's hands (if the hands have been coughed on or touched the mouth). The most contagious period is usually early in the illness, and shortly before the illness begins to show symptoms.

Generally yes,: as it is usually caused by a virus.

Depends....: There are many different bacteria and viruses that can cause acute bronchitis, each with a different incubation period and shedding time. So, the amount of time a person is contagious depends on which organism is causing the infection.