Officials in Sydney, Australia decided to extend a two-week lockdown to three weeks to protect the city’s largely unvaccinated population from the coronavirus and its delta variant.

As reported by NPR, less than 10% of Australian adults are fully vaccinated.

“We extended the lockdown to give us the best chance of not having another lockdown,” says New South Wales Premier Gladys Berejiklian.

Residents of Sydney and the surrounding communities will be under lockdown through July 16th due to the delta variant. This prevents students from returning to class after a summer break.

According to city officials, more than 50% of the 27 new cases they reported on Wednesday were not in isolation while infectious.

There are currently 37 COVID-19 patients in Sydney’s hospitals; 7 are in critical condition including individuals in their 30’s.

Experts traced more than 300 recent infections in Australia back to a limo driver who tested positive in mid-June.

The delta variant (also known as B.1.617.2) was first detected in India. It is more contagious than the original virus. It is also more severe, carrying a hospitalization risk twice that of COVID-19.

According to the CDC, delta is on track to becoming the dominant form of COVID in the US and world. So far, the delta variant is in more than 95 countries and in all 50 US states.

“Every country that it has gone into up to now, you’ve seen an escalation in cases where it’s pushed aside the variant that was dominant before it,” warns America’s top COVID expert, Dr. Anthony Fauci.

Research suggests COVID vaccines produced by Pfizer, Moderna, and AstraZeneca are more than 90% effective against the delta variant.

“The high-level message is that the vaccines work, two doses work better than one and the more people who get vaccinated the better,” says Dr. David Dowdy, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.

Fully-vaccinated individuals who become infected with the delta variant tend to develop minimal symptoms. Still, World Health Organization officials have advised everyone to wear face masks regardless of vaccination status.

The CDC continues to recommend face masks only for individuals who are not fully vaccinated.