With the COVID-19 pandemic seemingly in the rear-view mirror, South Korea is witnessing a late-season resurgence of seasonal flu and the common cold this spring, with the number of patients five times greater than the average of previous years, officials said Monday.

According to government data, the ratio of patients diagnosed with or suspected of having seasonal influenza in the 19th week of the year -- May 7-13 -- came to 23.4 per 1,000, up 26.5 percent from four weeks earlier.

The 19th-week figure marks its highest number for that week of a year in the past eight years. Compared to the average from previous years, it is nearly 5 times higher.

"It seems infants and young children who weren't diagnosed with viruses associated with the common cold and flu in the past three years of the COVID-19 pandemic are experiencing it all at once," said Chun Eun-mi, a professor of internal medicine at Ewha Womans University.

"But it's nothing too serious as there are vaccines and medicines to these viruses and the spread is expected to curb as the weather gets warmer," she added.

Circulating now are, among others, human rhinoviruses and parainfluenza viruses, which cause respiratory infections in infants and young children, medical experts said.

The year 2019 was the last major flu year in South Korea before the COVID-19 outbreak; the patients figure then sharply fell from the 17th week onward, as the weather warmed up.

But this year, influenza and the common cold have not loosened their grip, the experts pointed out, with many citing as a key factor the near-exit of South Koreans from pandemic-era restrictions and personal emphasis on virus controls.

On May 11, the government announced an end to nearly all antivirus measures, starting from June. It already lifted the majority of mask mandates, including for public transportation and indoor spaces, early this year.

Korea reported 6,798 new COVID-19 infection cases for Sunday, including 22 imported cases, bringing the total caseload to 31,548,083, the Korea Disease Control and Prevention Agency said Monday. It reported 12 COVID-19 deaths on the day, raising the death toll to 34,687.