What if a program is hosted somewhere, and I have a sacrificial construct in play. If the host is trashed, can I use sacrificial construct to save the program?

I'm guessing no, but I feel like the rules on hosting are sketchy enough that I need to ask.

From the rule book the important part is bolded:

"If a host is trashed, all cards, counters, and tokens hosted on it are also trashed. This cannot be prevented. "

If the host card is a valid target for Sacrificial Construct however, you could choose to save the host (e.g. if the Corp is attempting to trash Djinn).

I imagine however, that you're attempting to save a Parasite or Caissa. As you can't prevent the ICE being trashed, there's no way to save the hosted card.

I struggle to think of where a parasite would go if somehow saved.

I struggle to think of where a parasite would go if somehow saved.

This is probably why that rule exists, though you can imagine people trying to argue that they could immediately re-host it on another rezzed ICE

Although five bucks says that we'll get a Parasite 2.0 which does exactly that as a printed ability.