I think two waves are inevitable. But the second wave will be effected by herd antibody, as your story points out, they dont have one.
Nature is going to try to live,this virus is no different. It's the reason why we need medicines to weaken its ability to cause great harm, and shorten it.
But ultimately, the vaccine.
The herd effect is the most costly effect, because it has to effect large amounts of the population, but keeping the curve down, it allows for the herd effect, plus best helps from our health systems without being overcome,yt over a longer period of time, reach the same numbers if it were unencumbered.
But, the herd effect is like a spiderweb, where we're all connected, but those with antibodies act as cut off points within the web, as the virus tries to expand, it hits enough dead ends where it never reaches certain places or people. Thats the natural effect,the survival effect.