Chickenpox is caused by the varicella-zoster virus infection, and it can be transmitted in two ways. One way is through the secretion of the nasopharynx, such as contagious droplets spread by coughing, sneezing, or talking, which can infect people nearby. The fluid from the blisters of chickenpox is also contagious. The primary rash of chickenpox consists of blisters, and before these blisters dry up and crust over, touching the fluid from these blisters can also transmit chickenpox. Therefore, patients with chickenpox need to be isolated until the blisters dry and form crusts before quarantine can be lifted.