You can be rational and calm but still worried.
There is no cure other than your body's own defences ,oxygen may help.
It's looking like 3% mortality in developed countries apart from Italy which is having a dismal time of things.
In less developed countries with poorer facilities it may well go higher.
It seems to be more lethal to older and those with medical conditions but I wouldn't take too much comfort from that as no family is without the old and the sick or the unlucky.
We won't really know if any country has handled things better than others until it's history, a lock down now looks successful in Korea but you can't sustain it forever and anyone who has seen a graph of the Spanish flu epidemic will be alarmed at the second wave.
The herd immunity thing is getting a lot of stick but the science tends toward there being truth in it. It's brutal, may have been poorly expressed but until a vaccine is found every large country on the planet is basically going down that path even if they don't admit it because there's nothing else.

I'm no doctor but one piece of advice I've seen, (Dr John Campbell) on YouTube recommends vitamin D. Most people have a deficiency and a daily oral dose has proven to be efficacious in worthwhile studies against getting, and severity of respiratory viral and bacterial infections and by quite some degree.