Sydney has recorded 145 new Covid-19 cases overnight, with 51 people out in the community while infectious.
Premier Gladys Berejiklian told a press conference on Monday morning that the source of the infection for 79 of the new cases is still under investigation.
Fifty-five of the cases are linked to household contacts of known cases, and nine were other close contacts.
Chief Health Officer Dr Kerry Chant said the number of unvaccinated people over the age of 60 is 'distressing' and urged everyone in the age bracket to make an appointment immediately.
'When I review the numbers, to see how few over even 60-year-olds and over 70-year-olds we have managed to reach,' she said.