Highly-anticipated mainland Chinese film “The Battle at Lake Changjin,” which was due to have been released later this month has been postponed to an unspecified date. The move, announced late on Thursday, was caused by a recent resurgence in COVID-19 cases in China.

The film is a Korean War epic that is co-directed by Chen Kaige, Hark Tsui and Dante Lam and should have released on Aug. 12.

Its postponement will further undermine the Chinese box office, which started the year strongly but has been stagnating through the summer. Consultancy, Artisan Gateway this week reported that China’s year-to-date box office aggregate, at $4.65 billion, is running at 17% below pre-pandemic 2019 levels.

In many years, parts of July and August are reserved for Chinese-language movies in what is known as a film promotion month. This year has seen a particularly heavy crop of nationalist and propaganda titles reflecting the centenary of the founding of the Communist Party of China. Many of the largest Hollywood titles that are lighting up box office overseas have not yet been given release dates for mainland China.

The new virus wave is also hitting China’s film festivals. On Thursday it was announced that the eleventh edition of the Beijing International Film Festival, and the sixth edition of the Jackie Chan International Action Film Week have also been postponed.

The Beijing festival is normally held in April, but this time was shifted to Aug. 14.-21, 2021. Its lineup was announced last month, and Gong Li had been set as the president of the jury that would decide the Tiantian Awards. The Jackie Chan festival was to have been held Aug. 6-8 in Datong.

The latest virus outbreak is sparked by the highly infectious Delta Variant and is the worst that China has endured since largely bringing the disease under control a year ago. The outbreak began in in Nanjing, Jiangsu Province, and has since spread to 15 provinces and cities, including Beijing.

The numbers are small in comparison with many other countries. But the new wave is certain to hurt the theatrical film industry.

On Thursday, the China Film Administration released a notice requiring mainland cinemas to strictly implement disease prevention measures. Cinemas in high- and medium-risk areas must close while those in low-risk areas should limit their seat occupancy rate to 75%.

On Friday, China’s National Health Commission reported 124 new confirmed cases, including 44 imported cases and 80 local cases (61 cases in Jiangsu, 9 in Hunan, 6 in Hubei, 1 in Inner Mongolia, 1 in Henan, 1 in Hainan and 1 in Yunnan) and no new deaths.