Chickenpox is a very infectious agent that can easily be spread from person to person by coming contact with the virus present on the infected person or its belongings. It is caused by the varicella-zoster virus. Normally it occurs in children but adults can also get affected.
Red rashes with itchy blister are formed on skin in this infection and over the time the blister leaks which contain infectious virus. After 10-21 days of incubation, symptom appears and normally the patient recovers itself within 2 weeks.
So Christopher might get chickenpox from coming contact with the infected child during spending time in his child daycare so here chickenpox represent the link of infectious agent.
CONTACT TO SKIN WHICH MEANS ANOTHER KID AT THAT DAY CARE HAD TO HAVE THE CHICKEN POX AND WHATEVER THAT CHILD HAD TO TOUCH ( FOR EXAMPLE SAY IF THAT INFECTED CHILD TOUCH A CHAIR AND CHRISTOPHER TOUCH IT)
