Advertisement State and federal health officials have asked older Sydneysiders who have had their first AstraZeneca jabs to come back early for a second dose in response to the circulation of the Delta variant of COVID-19. NSW Chief Health Officer Kerry Chant has said people should consider shortening the interval between first and second jabs from 12 weeks to six. “We might sacrifice a bit of long-term protection but we’re making sure you’re protected earlier and, at this time, that’s the strategy we’d suggest,” she said. The call was backed by Australia’s Chief Medical Officer, Paul Kelly – but only for people living in Greater Sydney. Why?