You can get temporary immunity that lasts for a year or so and still be able to get reinfected multiple times in your life.
Yes. I'm talking about the question of immunity, not whether or not it's possible to get re-infected by new strains of the same virus, or whether or not immunity fades over time. It would be unlikely that this virus didn't confer at least short-term immunity to the host.
The viruses that cause colds primarily re-infect because they mutate at a very high rate. We aren't seeing that with this particular virus.
https://translational-medicine.biomedcentral.com/articles/10...
This is not claimed anywhere in the paper you linked to. They show a non-synonymous mutation in RNA-dependent RNA polymerase, and hypothesized that it could impact drug resistance.
> We found that viral strains with RdRp mutation have a median of 3 point mutations [range: 2–5], whereas viral strains with no RdRp mutation have a median of 1 mutation [range: 0–3] (p value < 0.001, Mann–Whitney test). The different distribution between the two groups relative to the number of mutations is statistically significant (Fig. 4).
No. As the person you're responding to pointed out: "The viruses that cause colds, many of which are also coronaviruses, are pretty adept at hitting people throughout their life."