A Covid-19 modeller says the number of Omicron cases could double by the end of the weekend.

Yesterday there were 105 new community cases - 15 of which were confirmed to be the Omicron variant, bringing the total number of Omicron cases to 105 also.

Professor Michael Plank said Omicron cases tended to double in two to four days at the start of an outbreak.

"We could see numbers continue to shoot up into the several hundreds over the next week or so."

Some of the community cases confirmed to have the Omicron variant attended large events which scientists say could cause the outbreak to spread more quickly.

Vaccination centres operating over Auckland Anniversary weekend

Nearly all vaccination centres across Tamaki Makaurau will be open over Auckland Anniversary weekend, to allow people to get their booster doses and to have their tamariki immunised in time for the start of the new school year.

Northern region clinical director Anthony Jordan said more than 300 GPs and pharmacies across the city were delivering paediatric vaccinations.

He said it was paramount children were protected, with school staring next week and Omicron in the community.

Jordan said vaccinations would reduce the spread and severity of the variant.