What was the first sci-fi work to have a virus that only infected computers?

Question

In the Wikipedia entry for the original 1973 Westworld it mentions the computer scientist scoffing at the idea of 'an infectious virus that affects computers'.

Is there an earlier than this sci fi work (novel or film etc) that mentions a virus that only infects computers?

Extract from the Wikipedia​ entry:

The technicians running Delos notice problems beginning to spread like an infection among the androids: the robots in Romanworld and Medievalworld begin experiencing an increasing number of breakdowns and systemic failures, which are said to have spread to Westworld.

When one of the supervising computer scientists scoffs at the "analogy of an infectious disease," he is told by the chief supervisor "We aren't dealing with ordinary machines here. These are highly complicated pieces of equipment, almost as complicated as living organisms. In some cases, they've been designed by other computers. We don't know exactly how they work."

Answer 1

I'm not aware of an earlier work.

As Wikipedia notes in its article on the great British SF writer John Brunner (1934-1995), “Brunner is credited with coining the term 'worm' and predicting the emergence of computer viruses in his 1975 novel The Shockwave Rider, in which he used the term to describe software which reproduces itself across a computer network.”

The Shockwave Rider was impressively ahead of its time and has been described as a precursor to William Gibson's Neuromancer and the cyberpunk movement it inspired.

John Brunner was a writer of remarkable versatility, ambition, and skill who deserves to be better remembered. His death at only 60 years of age was a tragedy for the SF field.

John Brunner, novelist