SANTIAGO, June 10 (Reuters) - Chilean health authorities announced a blanket lockdown across the capital Santiago on Thursday following some of the worst COVID-19 case numbers since the pandemic began, despite having fully vaccinated more than half its population. The development, which will alarm authorities elsewhere who are debating how fast to reopen as vaccination campaigns gather steam, comes as Chile's confirmed daily caseload surged 17% in the past two weeks nationwide and 25% in the Metropolitan region that includes Santiago and is home to half the country's population. Intensive care beds in the capital region are now at 98%...