Aged care quality and safety commissioner Janet Anderson revealed 371 COVID-19 linked complaints were received in March and 760 in April.

The number of complaints eased in May, she added.

Nearly half of all complaints from January to May have related to visitor access, while others focused on the preparedness of aged care facilities for the virus.

"That's probably unsurprising because families are used to accessing their loved ones in care without restrictions, so any constraint on that is going to come as a bit of a shock," she told a Senate inquiry into the government's virus response on Wednesday.

Ms Anderson praised the aged care industry code, implemented earlier this month, which has helped ensure families and carers can visit residents in nursing homes.

Before that there were eight different versions of visitor restrictions around the country.

Close to 30 per cent of all the coronavirus deaths in Australia have been in aged care facilities.

This proportion is much greater overseas, hitting 67 per cent in Spain, 62 per cent in Canada and 51 per cent in France.

Chief medical officer Brendan Murphy said there had been just over 30 residential aged care facilities affected by COVID-19 in Australia.

"Two of these facilities have experienced a substantial number of cases, which sadly involved a number of deaths in residents," he said in his opening statement.

"The other facilities have had a remarkably small number of cases among residents or staff, typically only one or two cases with no onward transmission."

About 70 people have been infected with the virus at the Newmarch House nursing home in western Sydney, and 17 residents have died.

Newmarch House and two other NSW aged care facilities where residents have died from the coronavirus, Dorothy Henderson Lodge and Opal Care Bankstown, will form part of the aged care royal commission's investigation into the impact of the pandemic.

Australian Associated Press