“Potential links to diplomats, aircrew and other people who may have had contact with international travellers have been investigated and no source of the Avalon cluster has been identified at this point,” a spokeswoman said. She said all exit screening tests on people who had been self-isolating on the northern beaches during that period came back negative. Advertisement “Questions around reciprocal arrangements with foreign governments overseas should be directed to the Commonwealth government,” she added. Federal Chief Medical Officer Professor Paul Kelly has previously expressed confidence that the northern beaches strain derived from a female traveller in hotel quarantine who arrived in Australia from the United States on December 1.