The QR code has turned COVID-19 check-ins into a golden opportunity for marketing and data companies

Tens of thousands of small and medium Australian businesses that rushed to outsource the management of their COVID check-in obligations could find themselves snared in a looming data privacy calamity.

At stake are the personal details of millions of Australians who have visited cafes, restaurants and pubs or attended places of worship, wedding and funeral venues since rules designed to help manage the spread of the virus were introduced earlier this year.