Yeah I think people forget that early on in Italy and NY all of the hospitals were overwhelmed. And they brought in refrigerated trailers to store the dead bodies that were piling on so fast.It's also easy to forget the status of hospitals & health care workers who were on the front lines.
If I can take a shot that may keep me out of the ICU, then it seemed the responsible thing to do.
At the time very little was known. So that is one of the reasons the guidance kept changing as we learned more and more.