Royal Mail (quoting Public Health England) have put out a statement.
Public Health England (PHE) has advised that people receiving parcels are not at risk of contracting the coronavirus. From experience with other coronaviruses, we know that these types of viruses don’t survive long on objects, such as letters or parcels. This complements the highly publicised guidance from PHE for people to wash their hands more often than usual using soap and hot water.
https://www.royalmail.com/coronavir...C7jJOLCouMT9XxJiXL4MHM2I02gU099kiF41v3EyqDjT0
Interestingly my usually unflappable postie had a parcel for me - rung the door bell, and left the parcel on the doorstep and then stepped back. When I opened the door he apologised and said he couldn't hand the parcel to me.