A pilot program to allow some international students to return to Australia's most populous state is likely to exclude Chinese nationals due to rules surrounding vaccination status.

The phased plan was approved by the federal government and the first flight carrying some 500 fully-vaccinated international students will arrive in New South Wales by the end of the year, the state government said Friday. Chinese nationals are Australia's biggest source of international students but they are likely to be ineligible to participate, because China's vaccines are not recognized by Australia's Therapeutic Goods Administration.

"They will need to be double vaccinated with a vaccine that our federal authorities deemed to be adequate and effective and that is just the way it is," Premier Gladys Berejiklian told reporters. Those wanting to participate in the future need to "find access to a vaccine that is regarded as effective by our authorities. We don't want additional risk put into our system," she said.

International education was worth A$14.6 billion ($10.7 billion) to New South Wales in 2019, the state government said. Macquarie University, The University of Newcastle, The University of Sydney, University of New South Wales (UNSW) and University of Technology Sydney (UTS) are among the universities that will participate in the pilot plan.

More than 57,000 students are estimated to be overseas, according to the state government. Chinese nationals are Australia's biggest source of international students followed by those in India, Nepal and Vietnam, according to the Australian Trade Department.

Vaccines made by Beijing-based Sinovac Biotech Ltd. and state-owned Sinopharm are among the most used in China, and have efficacy rates ranging from around 50% to 80% in preventing symptomatic Covid. A vaccine developed by Sichuan Clover Biopharmaceuticals was found to prevent 79% of Covid-19 cases caused by the delta strain in late-stage trials.

Sinovac and Sinopharm have provided little conclusive data on the effectiveness of their shots against the delta variant, which is more infectious than the virus' original strain and appears to have dimmed the protection of existing vaccines.

New South Wales state capital Sydney has been at the epicenter of a delta outbreak that's forced Australia's largest city into lockdown for the past 90 days and spread to Melbourne and other east coast areas. On Friday, New South Wales reported 1,043 new Covid-19 cases in 24 hours, with 11 deaths. Victoria, Australia's second-most populous state, reported 733 new cases and 1 death.