This is what the CISCE said in its notification:
"In view of Covid-19 spreading across the country, and with much uncertainty and speculation in the air, the Council, in the interest of the health and well-being of the students and the tesching community, has decided to postpone all ICSE and ISC 2020 exam scheduled to be conducted between the period March 19 to March 31, 2020.
The ICSE 2020 exam was scheduled to end on March 30 and the ISC 2020 exam was to end on March 31.
The revised dates for conduct of the remaining papers shall be notified in the due course of time. The heads of schools are required to ensure that sll concerned candidates, teachers and parents are informed immediately."