A six-day lockdown took effect Wednesday in the South Australian state after a cluster of new COVID-19 cases in the capital, Adelaide, grew to 22 people.

Only one resident per household will be allowed to leave their homes, and only for specified reasons, while mask wearing is mandatory. All schools and universities, pubs, takeout food services and cafes and restaurants are closed, as well as all factories except for food and medical products.

Outdoor exercises are banned, as well as open real estate auctions, weddings and funerals.

South Australia state Premier Steven Marshall described the six-day lockdown as a “circuit breaker” so that the state can “stay ahead of the virus.”

The cluster has been linked to a failure at one of the state’s quarantine hotels, where international travelers are required to isolate for 14 days upon arrival.

Elsewhere in Asia, South Korea reported 313 new coronavirus cases on Wednesday, the first time the country has posted more than 300 new cases since late August.

The new cases raise South Korea’s total number of COVID-19 infections to 29,311, including 496 deaths. The government announced Tuesday that it was imposing new social distancing rules for the greater Seoul area after the capital city recorded 200 new COVID-19 cases for three consecutive days.

Authorities in Tokyo reported a single-day record of 493 new infections on Wednesday, surpassing the Japanese capital’s previous high of 472 posted on August 1.

The resurgence of new COVID-19 infections around the world has led to a new grim milestone, with France becoming the first country in Europe to surpass 2 million total confirmed coronavirus infections.

Jerome Salomon, the director of France’s national health agency, put the exact count Wednesday at 2,036,755 confirmed cases, including 46,273 deaths. But Salomon said the country’s latest mitigation efforts “are starting to bear fruit,” with the number of new cases declining in recent days.

Meanwhile, another potential COVID-19 vaccine has shown promise after undergoing early and mid-stage clinical trials.

A study published Wednesday in the medical journal The Lancet Infectious Diseases found that 700 volunteers who were inoculated with CoronaVac, developed by Chinese-based drug maker Sinovac, appear to be safe and well-tolerated after being given to 700 volunteers who took part in a controlled trial.

The study also found that CoronaVac is capable of producing a quick antibody response within 14 days of receiving the second of two injections.

The experimental vaccine is currently undergoing third and final widespread clinical trials in Brazil, Indonesia and Turkey.

Two other potential coronavirus vaccines, one developed by U.S.-based Moderna and the other a joint collaboration between U.S.-based Pfizer and Germany’s BioNTech, have each reported a high efficacy rate above 90% this month.