Replies on Your Dog Bit Someone and Out of Date on Rabies Vaccine?

I can see why that was confusing. Generally, with any killed virus vaccine, one isn't enough to establish immunity, so a second is typically given (the "booster") a month or a few months later, often at the one year birthday. Then, a titer is taken to be sure there's immunity, and if there is, more vaccinations don't "boost," due to the immunity that's present and established. That immunity "sees" the vaccine virus and negates it, so it doesn't get a chance to elicit a booster effect.

2+ years later? Probably a bit long, but if immunity is your goal, I'd do it and follow with a titer test in 3-4 weeks. That'll tell you if you've gotten solid immunity or not.