According to images provided by the Centers for Disease Control and Prevention (CDC), Japan's pertussis epidemic continues to worsen, with reported cases rising to 2,660 as of May 25, marking the highest number since statistics began. The Japan Broadcasting Corporation (NHK) reported that the number of new infections in the past week increased by 361 from the previous week, setting a record not seen since 2018, surpassing the peak of over 17,000 cases in 2019.

By prefecture, the highest numbers of patients are located in Niigata with 148 cases, followed by Hyogo with 139, and Tokyo with 128. Pertussis is a bacterial infection that causes severe, persistent coughing, which can be fatal, particularly for infants under six months of age. This year, the total number of pertussis cases in Japan has reached 22,351, more than five times last year's figure.

Prof. Akihiro Saito from Niigata University highlights that pertussis has a very high infectious rate, with a basic reproduction number (the average number of people an infected person can transmit to) ranging from 12 to 16, comparable to measles outbreaks.

Pertussis is characterized by continuous coughing that produces a 'whooping' sound upon deep inhalation after a cough. One reason for the surge in cases is its high contagiousness. Additionally, there are indications that drug-resistant strains of the bacteria have been spreading in Japan since last fall.

This year, at least two newborns in Japan have died due to pertussis infections because they were too young to receive vaccinations. Experts urge that washing hands and wearing masks have limited effectiveness against highly contagious pertussis, and vaccination is the most effective prevention method, especially for infants who can receive a five-in-one vaccine beginning at two months old.