Hamilton’s contact tracing criticized by York University researchers

Research done by York University warns against interruptions to contact tracing, such as Hamilton public health no longer reaching out directly to all close contacts of cases.

“To be effective, it needs to happen quickly, widely and without interruption following the initial diagnosis,” says distinguished research professor Jianhong Wu, director of the faculty of science’s Laboratory for Industrial and Applied Mathematics (LIAM). “While Ontario is in its current lockdown, it’s particularly important that it enhances its contact tracing efforts now to get ahead of the situation before a reopening.”

As COVID cases increased in Hamilton last month, public health said contact tracing was no longer doable so it was now asking those who test positive to tell close contacts themselves.

“We will followup directly with any close contacts who are identified as working or residing in higher-risk settings,” public health said in a statement April 7, giving examples of seniors’ homes and other congregate settings, health-care workers and school or child-care staff.

“We also followup if the case indicates they cannot or will not inform their close contacts of the need to quarantine.”

Hamilton public health also uses letters to notify contacts in schools and child care when an entire classroom cohort needs to isolate.

However, Wu said both scenarios would be considered an “interruption” to contact tracing.

“In my humble opinion, the tracers must notify the contacts,” he said. “Only these tracers can also make sure the requirement that ‘the traced individuals should be self-isolated immediately and tested quickly’ be effectively communicated to the traced.”