SYDNEY, Australia—Sydney’s St Vincent’s hospital has been forced to chase down hundreds of people after it sent more than 400 incorrect negative COVID-19 results on Christmas Day. There are concerns those who received the false-negative result on Saturday night were then infectious in the community before being alerted to the error on Sunday. The hospital said its pathology unit immediately started the process of contacting the positive cases as soon as it became aware of the issue in the morning. “An emergency response team is now investigating the cause of this mistake, which is believed to be human error,” a statement issued on Boxing Day said. “We sincerely apologise to all those impacted.” The results pertained to tests taken on Wednesday and Thursday. Testing labs across the state are under pressure due to high demand with an average of about 145,000 swabs a day over the past week. Daily tests …