AstraZeneca Plc’s vaccine for Covid-19, once expected to be a mainstay of protection for much of the world, remains shrouded in controversy as more countries limit its use even as regulators and scientists attest to its benefits.The Netherlands joined a growing list of about a dozen places, including northern Italy and Ireland, moving to suspend the shot over concerns about possible side effects from two batches. While regulators from Europe to Asia said there was no indication of any direct link with the vaccine, reports of serious blood clotting after inoculation triggered a spate of suspensions stretching as far as Thailand.The safety scare emerged against a backdrop of supply woes, and continue a drumbeat of bad news that started with questions about its initial trials and now extends to its potential faltering efficacy against a novel variant. Even as some countries suspend its use, others like the U.S. are moving to protect their own stockpiles, blocking efforts to redistribute the shot’s supply to places with urgent needs.