Hello @Emma690
The whole world is in a dire situation including small businesses such as ours.
My heart goes out to all those who have lost and will lose their loved ones. My focus at the moment is on my loved ones and my communities and doing what I can personally to minimise the risk of this horrible virus from spreading.
I have blocked my listing for the next few months as I don't want to, even in a small way higher the risk by having visitors from all over coming to my listing and mixing with my local community.
As you said there will be local key workers who will need to continue to work and may need local accommodation.
You need to do what is right for you and yours. If those staying with you can't afford to pay the going rate which covers your core costs you may need to ask them to move on if their family and friends can't help them pay the market rate, it is not your job to subsidise them.
By the way Airbnb are returning all fees for cancelled bookings so will be losing a huge amount managing this situation. Let's hope it doesn't affect the viability of their business.