Late 70s/early 80s sci-fi novel about a young man in a post-virus world trying to find a safe haven

Question

The cover was colorful and had a picture of the back of a young man walking with a bike.

The story starts out with a teenage male living with his very paranoid father who has managed to keep them both alive with very strict rules in order to stay safe, not just from the virus (I think they called it the ceph/seph...sp?) but from people who once infected became irrational and violent. The father is exposed and sets into motion the plan for the son to reach a safe haven. The son manages to reach a safe place but is so unhappy with it after arriving that he leaves.

The book is actually quite short. I bought it in the mid to late 80s used at the Hobbit in Santa Monica. Read it till it fell apart and would love to remember the title so I can get a new copy.

Answer 1

You've come very close to the answer: it's Blakely’s Ark by Ian Mac Millian, published in 1981.
As far as I remember, the virus was called "Cepha", so your memory serves.

The setup is way more interesting than the bulk of the story but it's still a very good book that you read quickly.

Update - I've searched the Internet for a link but couldn't find anything. So I wrote a short summary of the book to check with your memories:

Dave lives with his father in a rundown suburb around Buffalo. Society has fallen down several years ago due to a very contagious virus: no cure has been found. But no problem, as Dave has a thick plot armor: he's immune.

.

His father dies soon, after a vagrant comes through the suburb and spreads the virus, despite his father's attempt at avoiding it. When he's dead, Dave leaves with his bike and rides to New York where the titular Ark is: it's the last bastion where humanity lives safely. Along the journey he has several encounters.

.

When finally Dave reaches the Ark, he finds it's surrounded by layers of slums, which form several rings of progressively safer zones around the Ark.

.

At last Dave is let in (or enters by subterfuge), then flees or is driven away: and he also leaves the slums just in time, as the Ark (which has been breached by the virus) is gassing the slums in an attempt at containing the virus.

.

In the end Dave finds more kids who seem to be immune too and founds a new community with them.