That Baise in the Guangxi Zhuang autonomous region reported 98 positive cases after finishing citywide nucleic acid testing on Sunday noon, and another 87 cases are awaiting re-examination for final confirmation of whether they are positive or not, should serve as a wake-up call not just to the authorities but to society as a whole that the virus will seize the opportunity of the holiday travel to spread if given the slightest chance.

The city, home to 3.57 million people and a border port to Vietnam, was locked down on Monday, a necessary move to avoid spillover. Now is time for the localities, especially the rest of Guangxi and neighboring Guangdong province, where most migrant workers from Guangxi earn their livings, to trace the close contacts and sub-contacts of the infected persons over the past three weeks at least — since experts warn that the cluster transmissions might have been going on in Baise for a week or so — to cut the transmission chains and verify the origin as soon as possible.

As such, the epidemiological investigation would have to span a period that started in mid-January, two weeks before the Spring Festival holiday began. That involves almost the whole population movement in the Pearl River Delta region, one of the most robust growth engines and densely populated regions in the country, during the peak travel season.

That makes the infections in Baise more worrisome than the sporadic cases in Shaanxi and Henan provinces and Tianjin and Beijing, which appeared and were quickly controlled before the Spring Festival travel rush commenced.

Given that there were more than 600 cases reported in Hong Kong on Monday, a new daily record for the special administrative region since the virus was largely tamed there over a year ago, special attention should be paid to address the resurgence of the virus in the Guangdong-Hong Kong-Macao Greater Bay Area, particularly in such comparatively less-developed regions as Guangxi.

Although many local governments encouraged migrant workers to cancel their trips home during the Spring Festival holiday, the traffic jams on inter-city expressways in many parts of the country on Sunday, the last day of the holiday, highlighted that the population mobility over the Spring Festival holiday this year has been on a much larger scale than that of the same periods of the holiday in the past two years, heralding the possibility of the virus popping up around the country.

It should not be forgotten that although China might be one of the safest places in the world, it has never been exempted from waves of the virus' variants. That these waves have been quickly contained before they could swell beyond control is due to the country's strict and dynamic epidemic prevention and control measures.

The relatively high number of infections in Baise should be a reminder to people of how far the country has come to reach where it is now in the fight against the virus and the harshness of the battle to maintain that advantage. Any slackening of vigilance could undo all the previous work. Therefore, there can be no complacency.