It is simply not true that the virus does not survive outside the body. Scientists have found that it does - on some surfaces it survives for hours, on others it is days. Regard everything coming into your house as potentially infected, including the post. Obviously you can not spray a letter but wash your hands after handling it.
As far as risk is concerned, there is risk and high risk. I believe that people who are in the high risk category are going to be contacted in the near future, but I don't know if that is true. Obviously it is going to be people like cancer sufferers, etc. Others, like me, are in the risk category. My heart condition doesn't make me more likely to catch it but, if I do, it can make the illness worse. But most of us are in the risk category by virtue of being old! Our immune systems don't work so well . That's why more of us die of pneumonia if we catch it, even without the virus.
Be extra fussy. It just takes a bit of time and it could keep you safe.