The recent COVID-19 outbreaks in China were the result of imported cases arriving via multiple transmission chains and complex sources, posing a huge challenge to prevention and control work, a health official said.

Wang Hesheng, deputy director of the National Health Commission, said the fourth wave of COVID-19 began in December and has lasted 11 weeks and appears to be peaking now, with the number of reported cases exceeding 10 million per week worldwide. Neighboring countries have reported a surge in infections in recent months, placing pressure on prevention work in China.

Wang said that from January to February, the daily average of imported cases was 91, much higher than the daily averages of 22 in 2020 and 32 in 2021. Since March, the number has exceeded 200, with the highest single day so far in excess of 300.

This recent wave of COVID-19 is dominated by the Omicron variant and its BA.2 subvariant, which is more transmissible and more insidious than previous strains. Most Omicron cases show only mild or no symptoms, making early detection and control more difficult.

This wave of outbreaks coincided with the end of the Chinese New Year holiday, during which many people traveled, leading to the rapid spread of the virus. Perceiving the Omicron variant as less harmful, some areas relaxed control measures, which was the wrong move, he added.

Wang said that according to the experts, this wave is still at its peak and will not end in the short term. China faces a serious and complex virus control situation.