With South Korea having lifted its mask mandate in stages, the number of patients with respiratory infections -- especially infants -- has been rapidly increasing, data showed Friday.

According to the Korea Disease Control and Prevention Agency, the country saw a total of 13,268 patients hospitalized at 220 government-monitored medical institutions for seven weeks from March to April 2023. The figure is more than 13 times the 1,002 people hospitalized during the same period last year.

In particular, the number of flu patients surged from 23 in spring 2022 to 941 this spring, while the numbers of rhinovirus and adenovirus patients jumped more than 10-fold from 314 to 3,828 and 79 to 924, respectively. Most of the patients were infants and toddlers aged six and under, the agency added.

As of the second week of April, rhinoviruses were the most detected type of virus with 17.8 percent, followed by adenoviruses with 11.6 percent and human parainfluenza viruses with 10.8 percent.

In the second week of April, 267 patients were hospitalized for influenza, up 38 percent from 193 the previous week. The number of hospitalized patients with viral respiratory infections, including adenoviruses, rhinoviruses and respiratory syncytial virus (RSV) increased from 2,311 in the second week of April to 2,335 in the third week of April.

In order to prevent the spread of respiratory infections, the quarantine authorities advised people most importantly to follow basic personal hygiene rules such as cover your mouth with tissue or your sleeve when coughing; avoid touching your eyes, nose or mouth with unwashed hands; and wash your hands for at least 30 seconds with running water and soap.