The main risk I'd be worried about that people will engage in more risky behavior after the first but before the second dose. It's a lot easier to hold out and

The main risk I'd be worried about that people will engage in more risky behavior after the first but before the second dose. It's a lot easier to hold out and skip some fun activities if there's a goal 4 (or rather 6) weeks ahead than if it's 8 (or rather 10) weeks.