Well yes and no.
I haven't been on the tube for about four years (I'm a Londoner but just as close to overground as tube), purely because of my own preference that if i am going to be caught in something I'd much, much rather not be stuck underground for it.
I'm having second thoughts about ferries after a trip this month, too, but I'm not hysterical about it.
I avoid (a very few ) certain places especially at certain times and wouldn't make a beeline for big public events just at the moment.
But other than that mixture of rational and semi-rational personal choices, you have to live your life. Anyway, there's still plenty you can do that doesn't involve heading to where the crowds are.
In the end, if you're unlucky, you're unlucky. The price you'd have to pay to eliminate risk entirely would be too much. I like theatre, museums, foreign cities. I love sharing those things with the DC. I like that they love those things. I'm glad I've taught them caution but I don't want to transmit fear to them.