- Recent book. Maybe 5 years old?
- A biological virus ravages the planet.
- A digital virus (maybe it was just social media?) develops symbiotically with the biological one.
- Something about how the digital virus paves the way for the biological one. Then the biological one feeds into the power of the digital.
- Something about a person who wanders from city to city and spreads it.
- I saw the blurb/review in some retweet from William Gibson and didn't make note of the book!
Partial match: The Frontiers Saga: Fall of the Core (2015), by Ryk Brown. A series of novellas set before the Frontiers Saga, describing the origins of the "Bio-Digital Plague" that wiped out 80% of Earth.
Blurb of the second book, from Goodreads:
As the Klaria virus sweeps across the planet, leaving death, and destruction in its wake, officials search for the man responsible for the bio-digital plague, beginning with their only real lead, text messages sent by a man referred to only as ‘Unknown.’
For field reporter Hanna Bohl, the crisis has given her the opportunity she has always dreamed of… A shot at the big leagues of broadcast journalism.
More on the Bio-Digital Plague, from the wikia:
The plague started as a computer virus that infected the earth's networks. The majority of people on earth interfaced with the networks through the use of cybernetic implants. The virus used these implants to trigger chemical reactions in the brain that would caused a biological virus that would rapidly reconfigure cells and cause them to grow out of control similar to cancer resulting in massive internal and external disfigurement.
The mortality rate of the infected was 90% and the biological component of the virus was contagious itself. The virus rapidly mutated making it incredibly difficult to treat.
The creator of the virus was never discovered.
What doesn't match:
- The individual novellas are very short (about 50 pages each), I don't know if one would refer to them as a "book", but maybe they were collected in a single format
- I can't confirm the wandering person bit (yet)
- I can't confirm William Gibson knowing of it.
Found with the Google query
science fiction novel biological digital virus site:goodreads.com/book.