How to prevent signals (e.g., SIGINT via Ctrl-c) from affecting child process of bash script

Issue

• Example issue #1: interactive shell script spawns long-running process
  How to make the whole script, including this process, ignore Ctrl-c
  Example code:

  #!/bin/bash
  trap '' SIGINT
  ping -c10 localhost
  echo FINISHED
  

• Example issue #2: interactive shell script spawns a long-running process in the background
  How to make the whole script, including this process, ignore Ctrl-c
  Example code:

  #!/bin/bash
  trap '' SIGINT
  ping -c10 localhost &
  wait
  echo FINISHED
  

• Note that in both examples, the terminal will pass the Ctrl-c-triggered SIGINT on to the script's process group -- i.e., while the script itself will ignore SIGINT, the ping command will still receive it and exit early