Mr Morrison said states were in charge of securing the supply of rapid antigen tests, with the Commonwealth fulfilling its requirements despite complaints about their lack of availability.
"It was discussed at national cabinet in November ... so there was no confusion," he told reporters on Thursday.
"I'm not making a criticism of the states. I am just saying that you asked me whether the Commonwealth had done what is needed to do and I said, 'Yes we had' and now we are going further."
But University of Melbourne epidemiologist Professor Tony Blakely warned surveillance would not be accurate going forward with the tests mainly being done at home.
"The horse has bolted, this is the biggest policy failure so far in Australia," he told the Seven Network on Thursday.
But Mr Morrison said it was more important to connect people with care than reporting numbers.
"Case numbers are less of an issue (and) will be underestimated in Australia because we know that people are self-managing in many instances," he said.
"What matters first is that people who have COVID (is) the care they get connected to."
Mr Morrison said 200 million rapid tests would be available in coming weeks but ruled out making them universally free, instead providing 10 tests over a three-month period to concession cardholders, which covers more than six million people.
Labor senator and chair of a parliamentary COVID-19 committee Katy Gallagher hit out at the concession plan, saying the Australian pandemic response had been one where everyone was in it together.
"Huge amounts of funding has been provided to ensure we have been able to live safely. Providing rapid antigen tests to everybody is part of that approach," she told Sky News.
Infectious disease expert Professor Peter Collignon said getting a PCR confirmation of a positive rapid test doesn't add much, telling people to stay home and isolate if they have a positive test.
"If you're vaccinated and are a 30- to 40-year-old, your chance of coming into grief is really low. We have support if you need it but don't get on the (PCR) queue and delay the older people who may need to be in front of you," he told Sky News.
The prime minister had no apologies for the government blocking tennis world No.1 Novak Djokovic's entry to the country.
After the Serb's visa was cancelled within hours of arriving at Melbourne airport for the Australian Open, Mr Morrison said entry to Australia required double vaccination or a medical exemption, which Djokovic did not have, and that "rules are rules".
Djokovic's lawyers went to the Federal Circuit Court on Thursday afternoon to seek a judicial review of his visa cancellation.
Meanwhile, NSW registered another 34,994 new cases on Thursday and a further six deaths.
Victoria recorded a new one-day high for new cases, with 21,997 infections and six deaths.
There were also 10,332 new infections in Queensland, 3070 in SA, 992 in the ACT, 751 in Tasmania and nine in WA.
There were a record 222,565 booster shots delivered on Wednesday.
The prime minister used the record number to encourage parents to get their children vaccinated before schools returns at the end of January.
"So on the back to school list, on the fridge ... (it) says, get vaccinated," he said.
"Getting kids back to school is very important and getting their vaccination is very important."
National cabinet will meet again in a week's time to discuss getting kids back to school in a safe manner.
"Many states are already well advanced in their plans for achieving that," Mr Morrison said.
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