Capturing 10% of cases would put the US CFR of ~0.4% which is completely unsupported. Increasing that to even 30% so a 1.2% CFR and your talking 3.1 years which is well past estimates for an effective vaccine.

PS: Influenza vaccines are common with 68% of people over 65 getting vaccinated in the US. Further at least half of all cases are asymptotic which ends up contributing significantly to herd immunity.