The venue had not been enforcing social distancing, with footage which later emerged showing hundreds of drinkers packed into its beer garden.
A person who tested positive had visited the pub and then attended a private social gathering, further spreading the virus, Staffordshire County Council has previously said.
The 19 people who tested positive had all visited the pub or met others who had, said director of health and care Richard Harling on Sunday.
Dr Harling said: “The gathering that caused the spike is now a few weeks ago, so we are now looking more at incidents where pub-goers may have passed the virus on to a friend or loved one.
“All those who have been in close contact with the 19 confirmed cases are being contacted and if you are one of these people you must stay home for 14 days, even if you feel well or have tested negative for the virus.”
The council reminded everyone that failing to comply with the guidance could cause a more severe local outbreak.
Dr Harling said: “This outbreak shows how quickly the virus can spread when people don’t social distance, so it is important that everyone in Staffordshire follows the guidance to help prevent a second peak in infections here.”
The Crown and Anchor has since temporarily closed to “review [its] risk assessment” and an “overwhelming amount of people” visited on Saturday, 18 July.
Meanwhile, a cluster of 13 coronavirus cases linked to a pub in Aberdeen is investigated by public health officials.
NHS Grampian said the cases are associated with The Hawthorn Bar in the city’s centre.