* The Parafield cluster has been revised down to 22 confirmed infections with no new cases reported on Thursday.

* Another 17 people are thought likely to have the virus but are awaiting test results.

* Key areas of concerns include an Adelaide pizza bar, a car crash repair business, two cafes and a fabric store, with people who visited those locations at particular times asked to quarantine.

* Almost 40 other locations listed as places visited by confirmed cases in recent days, with people there at the same times asked to monitor for symptoms and get tested if they feel ill.

* So far 3200 people identified as close contacts have been placed in quarantine, with thousands more self-isolating.

* The outbreak was sparked by a woman who worked as a cleaner in the Peppers Hotel, one of Adelaide's quarantine facilities, who may have picked up the virus from a surface, and then infected other family members.

* Genetic testing has linked her case back to a traveller who returned from the United Kingdom on November 2.

* The first case was identified when an 81-year-old woman tested positive at the Lyell McEwin Hospital on Saturday.

* Thousands have flocked to testing stations around Adelaide, with more than 21,500 swabs taken over the past two days.

* Staffing and hours to be expanded at testing stations and two more sites to be established in Adelaide's west and north.

Australian Associated Press