The Korea Centers for Disease Control and Prevention issued a nationwide influenza warning early Thursday, with the number of patients seeking treatment surpassing normal rates.

An influenza warning is issued when flu patients number more than four out of every 1,000 patients. The number hit 4.8 earlier last week, up from 3.1 a month ago. The rate of detection for the influenza virus has also shot up from 2.5 percent in December to over 17 percent as of the middle of this month.

The H1N1 virus currently spreading across the nation is the same strain that struck Korea in 2009, but it poses a much lower threat than the H3N2 flu virus that has killed more than 100 people in the U.S.

The health agency says people do not need to be overly concerned because Korea has a relatively high vaccination rate, with over 16 million people already vaccinated.

"The vaccine developed this year fends off both the H3 virus from the U.S. and Korea's H1 virus, so we believe it will be effective," said Lee Jin-kook at Seoul St. Mary's Hospital.

Meanwhile, experts recommend that people wash their hands frequently and that children, the elderly and pregnant women who have not yet received the vaccination do so immediately.