SEOUL (Reuters) – South Korean chipmaker SK Hynix said on Thursday that 800 of its workers had quarantined themselves as a precautionary measure to prevent the of the coronavirus, but its production in the city of Icheon has not been affected.

The move came after one trainee had close contact with a virus in the southeastern city of Daegu, the epicenter of an outbreak in South Korea.

SK Hynix, the world’s No.2 memory chipmaker which Apple Inc and Huawei among its customers, said another trainee also had symptoms of pneumonia. The two trainees tested for the virus, but will undergo a second test.

A surge in confirmed cases linked to a local church in Daegu this week sparked fears of wider transmission.

The 800 include 280 trainees, who have not yet started working on production lines, and accounts for a fraction of its workforce of 18,000 in Incheon, a spokeswoman said.

SK Hynix has closed its training center and hospital in Icheon, southeast of Seoul.

(Reporting by Hyunjoo Jin; Editing by Kim Coghill and Himani Sarkar)