If your goal is just lowering R0, sure… but a lot of countries prefer to lower deaths, which is why they start with the older population / those with health conditions.
People with health conditions won't get infected if there is no spread. By all means vaccinate the most vulnerable, but stay at home early retirees aren't exactly superspreaders.
The 18-35 cohort after vaccination with the Pfizer vaccine are going from being extremely dangerous asymptomatic spreaders to having high levels of sterilizing immunity.
