During a fiery round of questioning at Senate estimates, Senator Colbeck said the number of deaths in aged care from the virus were not an indication of performance.
There have been almost 700 aged care deaths from COVID-19 since the start of the year, more than all of 2020, which had 685 aged care fatalities from the virus.
"We are in the middle of a global pandemic, and the completely tragic result of that is people will catch the virus across all parts of the community, and tragically, some will die," he told the hearing on Wednesday.
"The performance in managing COVID-19 has improved."
Senator Colbeck said he had not offered his resignation to Prime Minister Scott Morrison over issues in aged care.
It was revealed there were 915 COVID-19 outbreaks in aged care facilities across the country.
Of those, 479 have been in NSW, 148 in Victoria, 176 in Queensland, 85 in South Australia, three in Tasmania, six in the Northern Territory, 16 in the ACT and two in Western Australia.
He admitted that making changes earlier to staffing arrangements in the sector might have helped in dealing with the peak of Omicron cases.
Health officials also told estimates that between four and five per cent of the aged care workforce had missed shifts due to testing positive for COVID-19.
However, officials did not state how many facilities across the country had faced staffing issues due to the pandemic and rising Omicron infections.
The aged care minister said while there were issues in the sector that needed to be addressed, he criticised people who wanted to "talk down" aged care.
"Every time you tell (workers) how bad it is, you're saying how bad they are," Senator Colbeck said.
"Mistakes have occurred and we've acknowledged that."
The head of Australia's vaccine rollout, Lieutenant-General John Frewen, told the Senate committee all aged care facilities had been visited for residents to receive their booster doses.
About 450 sites have also had a second visit by the vaccination teams.
He said 80 per cent of the country's population over 70 had received a booster dose.
"The efforts for the booster in residential aged care and disability care is the highest priority," he said.
Opposition aged care spokeswoman Clare O'Neil said more support was needed for aged care workers.
"The prime minister when asked about the staggering number of deaths with COVID in aged care, his response is 'Well, a lot of people die in aged care anyway'," she said.
"I feel like we are on very dangerous territory - just because people are older it doesn't mean their lives don't matter."