Parts of Sydney will enter a fresh one-week lockdown starting Friday at midnight.Australian authorities are trying to tamp down a spike in the highly-contagious Delta variant of the coronavirus. The affected areas include the Sydney Central Business District, as well as the city's eastern suburbs, where the iconic Bondi Beach lies. Some doctors however warn the move is not enough.The Australian Medical Association called for a complete lockdown of the country's biggest city to avoid the virus spreading nationwide.But New South Wales, where Sydney is located, has held off calls for a hard lockdown.Instead they've again made masks mandatory indoors and limited home-gatherings to five.Total infections in the newest outbreak have so far topped 60. Authorities are also worried about a potential super-spreader event in a salon where three staff were infected, and over 900 clients visited last week. Officials issued health alerts overnight for more than a dozen new venues across Sydney. Australia's COVID-19 numbers have been relatively low, aided by lockdowns, swift contact tracing and strict social distancing rules. In response to the recent outbreak, New South Wales has been effectively isolated from the rest of the country.Other states like Queensland and Victoria have reinstated tough border rules, including a total ban for visitors from Sydney's virus-hit suburbs.Sydney is home to a fifth of the country's population of 25 million.