‘Pneumococcal serotype 3 prevalent among adults in Korea’

In Korea, pneumococcal serotype “19A” is commonly found in infants under five to adults over 65. However, serotype “3” is more prominently observed in adults, according to a study.

“Korea’s serotype distribution is completely different from that of other countries, such as the U.S., France, and Japan,” said Professor Shin Jeong-hwan of the Laboratory Department at Inje University Busan Paik Hospital at an online webinar, “Microbiological characteristics of pneumococcus aureus and the usefulness of vaccines,” held by Pfizer Korea last Wednesday.

As a result, pneumococcal vaccination that considers pneumococcal serotype distribution is needed, he added.

Professor Shin shared the latest knowledge on diagnosing invasive pneumococcal disease in Korea based on a study that collected and analyzed pneumococcal strains causing invasive pneumococcal disease from 16 hospitals between 2017 and 2019.

According to Shin, the most frequent serotype among those preventable by the 13-valent pneumococcal protein conjugate vaccine among infants aged five and younger in Korea was 19A, with 75 percent occurring in infants aged one or less.

"Serotype 3, which is most common in adults, especially those over 65, was rarely observed in infants and babies,” he said. “Differences in serotype distribution by age are attributable to the effect of 13-valent pneumococcal protein conjugate vaccination in infants and babies. Furthermore, it supports the argument that vaccination with 13-valent pneumococcal protein conjugate vaccine should be considered in the older population.”

In addition, as a result of analyzing serotypes causing invasive pneumococcal disease after the introduction of Pfizer’s pneumococcal vaccine (13-valent pneumococcal protein conjugate vaccine) in Korea, serotype coverage for 13-valent pneumococcal protein conjugate vaccine was broad, as shown by 28.7 percent of all ages, 14.0 percent of infants under 5, 30.6 percent of adults 19 years and older, and 33.9 percent of older adults 65 and older.

“Considering that the coverage of serotypes included in the 13-valent vaccine is very low in children five and younger, it is necessary to prevent pneumococcal infections with vaccines containing these serotypes across all ages,” Professor Shin said.

He pointed out that in infants and young children, pneumococci are the leading cause of invasive bacterial infections, including meningitis, which has a fatality rate of around 10 percent and can leave 20-30 percent of survivors with severe aftereffects.

“Pneumococcal vaccines are crucial to prevent diseases at this age,” Professor Shin added.