Six of the 23 patients in Korea who have tested positive for coronavirus were infected by members of their family, the Korea Centers for Disease Control and Prevention said Thursday.

Coronavirus spreads in the home because many patients with latent infections have relatively mild initial symptoms.

"When Middle East Respiratory Syndrome broke out, many patients were quickly hospitalized with severe symptoms in the initial stage, so the virus spread mostly in hospitals," said Prof. Choi Jae-wook of Korea University. "But coronavirus produces mostly mild symptoms like the common cold, and people who haven't been to China may not have seen the distinction and unknowingly spread it to their family."