Humza Yousaf defended the “sensible and practical” approach of sending text messages to contacts believed to be at low risk, freeing up contact tracers to call the more complex and higher-risk cases.
It follows a week of record-high infection numbers across Scotland – 25,107 new cases identified over the last seven days, with a peak of 4,234 announced on Thursday.
At Friday’s coronavirus briefing, First Minister Nicola Sturgeon insisted the contact tracing system was “coping well” but acknowledged it was “under pressure” because of the surging number of cases.
Mr Yousaf has confirmed a change in strategy on Saturday, with contact tracers being instructed to message “low-risk index cases” rather than speaking to people directly over the phone.
A Public Health Scotland report revealed that sending text messages with advice about self-isolating and getting tested became the “default” from June 18 because of rising numbers of Covid-19 cases.
The tracing of secondary contacts has also been dropped.
Attempts to increase the number of contact tracers – including further recruitment – is also taking place, according to the Scottish Government.
Mr Yousaf said: “The third wave of cases means that the Test and Protect system is now contacting record numbers of people each day.
“The shift in approach we are taking will mean more text messages going out and people getting online to report contacts and find information.
“This is a sensible and practical approach which will allow us to focus our contact tracing efforts on the most high-risk cases and prevent further spread of the virus.
“Contact tracers will continue to phone many of those who have tested positive but there will be a focus on more complex, high-risk cases.
“We continue to look holistically at the system to ensure its resilience, including supporting ongoing local recruitment and flexing additional workforce capacity within the National Contact Tracing Centre.”
He added: “It’s really important that people who are contacted by Test and Protect continue to self-isolate for 10 days.
“Our Test and Protect staff are doing fantastic work under significant pressure and we should all be thankful for their efforts throughout this pandemic.
“I would encourage anyone who has a smartphone to download the Protect Scotland App – if you test positive, you will receive a code that can be entered into the app, providing isolation notifications to people you have been in contact with.”
Following the announcement, Scottish Labour health spokeswoman Jackie Baillie said: “This news is an explicit admission that the SNP has failed to develop a robust test and protect system.
“They have failed to support the staff trying their best to cope with the surge in numbers.
“Rather than rising to the challenge of increasing cases, it has buckled under the pressure – risking our exit from the pandemic.
“It should not come as a surprise to anyone that cases would increase as restrictions lift.
“The government’s failure to prepare for this is a downright dereliction of duty.
“We urgently need to put the resources in place to make sure test and protect is able to cope and bring the spread of the virus under control.
“This means dedicating all the resources available to a full service to track the spread, not cutting corners and lowering standards in that fight.”
Scottish Conservative health spokeswoman Annie Wells added: “It’s quite clear the system isn’t working as it should be and is struggling to cope with the high number of cases which has prompted this move.
“People are understandably worried about the rise in case numbers and it’s imperative that no case goes unforgotten through this new way of working.
“The SNP have already taken their eye off the ball with Test and Protect which simply can’t happen again.
“A robust and effective system will play a critical role in helping to ensure people self-isolate as quickly as possible and give us the best chance of staying on track to ease restrictions over the summer.”