China’s Sinovac vaccine is quickly changing from a hoped-for diplomatic triumph to a sign that China isn’t yet ready for the global cutting-edge prime time. Initially hailed as the developing world’s trump card against Covid-19, the vaccine is suddenly facing an epidemiological crisis. Efficacy doubts have Singapore deciding people who received Sinovac should be characterized as unvaccinated. In Thailand, health officials claim more than 600 Sinovac-jabbed medical workers have tested positive for coronavirus. It’s an embarrassing turn for Xi’s “vaccine diplomacy” scheme – one that initially caught the US flatfooted. And it’s bigger than that. The Sinovac stumble symbolizes both China's growing number of policy mishaps as well as its broad tendency to put the quantity of growth ahead of its quality.