ACT has rescheduled the April 4th national test date with the following statement on their website:
The safety of students and test center staff is ACT’s top priority. ACT has rescheduled its April 4 national test date to June 13 across the U.S. in response to concerns about the spread of the coronavirus (COVID-19). All students registered for the April 4 test date will receive an email from ACT in the next few days informing them of the postponement and instructions for free rescheduling to June 13 or a future national test date.
See more info at: https://www.act.org/content/act/en/covid-19.html