If there is a need then you should be out there. Reframe it away from advertising and think about it more as helping.
Recent research says 79% of people want or expect brands and services to be advertising right now. So don’t feel you should be holding back.
Also other research shows that the brands that continue to advertise through a recession will grow faster and gain share (largely because they will have the greatest share of voice).
So don’t think of it as being advertising. Think of it as ensuring the people that need you know you are there, know you are open, know how you can help them.
You’re absolutely right you don’t want to be seen to be exploiting this situation but it only takes a small change in your messaging to ensure it is right for now.
Get out there. People need your help.