It's been a day of drastic measures, major escalations and confusing messaging in the nation's response to the COVID-19 pandemic.

Australia surpassed 1300 cases of coronavirus, including 533 in NSW.

The federal government announced a second, $66 billion stimulus package, which will double welfare amounts for those on Jobseeker, increase support for pensioners and carers and make $100,000 grants available to small and medium-sized businesses.

NSW announced it would go into lockdown by Tuesday, with all "non-essential" services to be closed. Victoria flagged similar measures, and both states said they would push for tough restrictions at the national cabinet meeting held on Sunday night.

Victoria said all its schools would close on Tuesday, two days ahead of when they were due to shut for school holidays. NSW was expected to make a similar announcement, with Premier Gladys Berejiklian still due to give an update on Monday morning.

South Australia and Western Australia closed their borders to interstate visitors, following the lead of Tasmania and the Northern Territory.

On Sunday evening, the national cabinet revealed tough new restrictions on places of gathering, with pubs, gyms, restaurants, cinemas and places of worship to close down as of midday on Monday.

The Prime Minister remained insistent that schools will not close, and it appears that NSW and the ACT may not shut down their schools in the coming week, as earlier expected. Victorian schools will still close on Tuesday.

There's a lot going on. But as Scott Morrison said in his press conference this evening, one thing's clear: the situation is now "deadly serious".

Follow along with the latest developments on Monday, March 23.