The recent outbreak of COVID-19 infections in Beijing and Dalian, Liaoning province, have a similarity: a connection to a seafood market or processing, an epidemiologist said on Wednesday.

In Beijing, the infections were related to the Xinfadi wholesale food market; in Dalian, many confirmed cases have been connected to people working at Kaiyang World Seafood Co. The initial outbreak in Wuhan, Hubei province, in January was tied to the Huanan seafood market.

"The three places all have moist, low-temperature environments," Wu Zunyou, chief epidemiologist at the Chinese Center for Disease Control and Prevention, told CGTN in a TV program in Chinese.

That type of environment is suitable for the survival of the virus, he said. When there is contamination, the virus can accumulate in certain areas and is not easily killed. And so there's a risk of transmission, he said.

According to Wu, Dalian has identified no new local COVID-19 cases for more than 100 days. The virus must have come from outside, he said.

Big data analysis has not established a definite relationship between the epidemic in Dalian and the outbreak in Beijing, he said. Nor is there any definite indication of a connection with imported cases from abroad.