The new Berala cluster cases were a man and a woman in their 30s and a child.
They were close contacts of a man and woman in their 30s reported on Sunday as positive cases who were identified after an existing case remembered holding a small gathering at her home on December 27, which she had not previously listed in contact tracing interviews.
Today's three reported cases interacted with yesterday's cases at another household gathering on December 29.
Dr Chant said NSW Health was investigating the series of events for possible subsequent infection events but was confident they had worked through the chain of transmission.