Australia is seeking to ramp up its COVID-19 vaccination drive as it battles a widening outbreak of the Delta variant.
The first local case of the highly contagious strain was detected in Sydney two weeks ago in a limousine driver who transported airline crew.
The outbreak has since grown to nearly 150 cases.
It's prompting other major Australian cities like Brisbane and Perth to join Sydney under lockdown, affecting over 20 million Australians.
"Last night we announced that as of midnight, Perth and Peel will be entering a four day lockdown. This full lockdown is designed to act as a circuit breaker to buy our contact tracers and testing systems time to gain a truer picture of how far this outbreak has spread."
Australia also announced new measures to try and boost its slow vaccination rate, including mandatory shots for aged-care workers and employees in quarantine hotels.
Officials are also making the AstraZeneca vaccine available to people under 60, after previously limiting its use to over-60s due to concerns of blood clotting.
Authorities now say people under 60 can request the AstraZeneca vaccine if approved by their doctors, who will be covered by a no-fault scheme similar to other practices seen overseas.
So far, Australia has kept its COVID-19 cases relatively low due to snap lockdowns, contact tracing and strict social distancing.