Red Cross Lifeblood donor centre network head Cath Stone says testing and quarantining requirements prompted by the Omicron outbreak, as well as the holiday season, were creating a "perfect storm" of cancellations.

"More than half of all appointments are not being attended, which means we need more donors to roll up their sleeves and take the place of those who can't donate," Ms Stone says.

While the holiday season always presents a challenge for Lifeblood donations, Ms Stone says "donor numbers have plummeted" as people isolate and wait for results of COVID-19 tests, with many people also travelling interstate and wanting to spend their time with family and friends.

The PCR test requirement for entry into a number of states, as well as a surge in the number of people being identified as close contacts and requiring testing, has caused a blowout in wait times with some results taking up to six days to return.

The Red Cross is calling for at least 3200 donors to give blood before January 3, with O and A blood types the most in demand.

"These blood groups make up nearly 90 per cent of patients in hospital and we need donors of these blood types to donate this week to maintain our supply," Ms Stone says.

Qld and NSW are the most in need of donors, with 1000 additional donors required in each state.

Blood donation centres are open every day around the country.

"It takes one hour to come and donate blood and it gives life and hope to somebody and their families for Christmases to come," Ms Stone says.

Trauma events, surgeries, cancer treatments, birthing mothers and newborn babies are among those in need of blood during the period, and Ms Stone says a donation is needed every 18 seconds around the country.

Australian Associated Press