Clinical Features and Risk Factors of Uveitis in Korean Children with Juvenile Idiopathic Arthritis: A Retrospective Cohort Study.

This study aimed to investigate the clinical features and risk factors of uveitis in Korean children with juvenile idiopathic arthritis (JIA). The medical records of JIA patients diagnosed between 2006 and 2019 and followed up for ≥1 year were retrospectively reviewed, and various factors including laboratory findings were analyzed for the risk of developing uveitis. JIA-associated uveitis (JIA-U) developed in 30 (9.8%) of 306 JIA patients. The mean age at the first uveitis development was 12.4 ± 5.7 years, which was 5.6 ± 3.7 years after the JIA diagnosis. The common JIA subtypes in the uveitis group were oligoarthritis-persistent (33.3%) and enthesitis-related arthritis (30.0%). The uveitis group had more baseline knee joint involvement (76.7% vs. 51.4%), which increased the risk of JIA-U during follow-up (p = 0.008). Patients with the oligoarthritis-persistent subtype developed JIA-U more frequently than those without it (20.0% vs. 7.8%; p = 0.016). The final visual acuity of JIA-U was tolerable (0.041 ± 0.103 logMAR). In Korean children with JIA, JIA-U may be associated with the oligoarthritis-persistent subtype and knee joint involvement.

Twenty-Five Year Trend Change in the Etiology of Pediatric Invasive Bacterial Infections in Korea, 1996-2020.

BACKGROUND: The coronavirus disease-2019 (COVID-19) pandemic has contributed to the change in the epidemiology of many infectious diseases. This study aimed to establish the pre-pandemic epidemiology of pediatric invasive bacterial infection (IBI). METHODS: A retrospective multicenter-based surveillance for pediatric IBIs has been maintained from 1996 to 2020 in Korea. IBIs caused by eight bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pyogenes, Listeria monocytogenes, and Salmonella species) in immunocompetent children > 3 months of age were collected at 29 centers. The annual trend in the proportion of IBIs by each pathogen was analyzed. RESULTS: A total of 2,195 episodes were identified during the 25-year period between 1996 and 2020. S. pneumoniae (42.4%), S. aureus (22.1%), and Salmonella species (21.0%) were common in children 3 to 59 months of age. In children ≥ 5 years of age, S. aureus (58.1%), followed by Salmonella species (14.8%) and S. pneumoniae (12.2%) were common. Excluding the year 2020, there was a trend toward a decrease in the relative proportions of S. pneumoniae (rs = -0.430, P = 0.036), H. influenzae (rs = -0.922, P < 0.001), while trend toward an increase in the relative proportion of S. aureus (rs = 0.850, P < 0.001), S. agalactiae (rs = 0.615, P = 0.001), and S. pyogenes (rs = 0.554, P = 0.005). CONCLUSION: In the proportion of IBIs over a 24-year period between 1996 and 2019, we observed a decreasing trend for S. pneumoniae and H. influenzae and an increasing trend for S. aureus, S. agalactiae, and S. pyogenes in children > 3 months of age. These findings can be used as the baseline data to navigate the trend in the epidemiology of pediatric IBI in the post COVID-19 era.

Changes in Etiology of Invasive Bacterial Infections in Infants Under 3 Months of Age in Korea, 2006-2020.

OBJECTIVES: Invasive bacterial infection (IBI) causes a significant burden in infants. In this study, we analyzed changes in epidemiology of IBI among infants in Korea. METHODS: A retrospective multicenter-based surveillance for IBIs in infants <3 months of age was performed during 2006-2020. Cases were classified as an early-onset disease (EOD) (0-6 days) or late-onset disease (LOD) (7-89 days). The temporal trend change in proportion of pathogens was analyzed. RESULTS: Among 1545 cases, the median age was 28 days (IQR: 12, 53) and EOD accounted for 17.7%. Among pathogens, S. agalactiae (40.4%), E. coli (38.5%), and S. aureus (17.8%) were the most common and attributed for 96.7%. Among EOD (n = 274), S. agalactiae (45.6%), S. aureus (31.4%), E. coli (17.2%) and L. monocytogenes (2.9%) were most common. Among LOD (n = 1274), E. coli (43.1%), S. agalactiae (39.3%), S. aureus (14.9%) and S. pneumoniae (1.3%) were most common. In the trend analysis, the proportion of S. aureus (r s = -0.850, P < 0.01) decreased significantly, while that of S. agalactiae increased (r s = 0.781, P < 0.01). CONCLUSION: During 2006-2020, among IBI in infants <3 months of age, S. agalactiae, E. coli, and S. aureus were most common and an increasing trend of S. agalactiae was observed.

Comparison of Antibody Response Elicited by ChAdOx1 and BNT162b2 COVID-19 Vaccine.

BACKGROUND: ChAdOx1 and BNT162b2 vaccines are currently commonly used against coronavirus disease 2019 worldwide. Our study was designed to determine the serostatus and relative levels of anti-S and neutralizing antibodies in patients who were administered either ChAdOx1 or BNT162b2 vaccine. In addition, we investigated whether the antibody response to each vaccine differed according to sex and age. METHODS: Healthcare workers (HCWs) at a general hospital who were vaccinated with two doses of either ChAdOx1 or BNT162b2 were invited to participate in this prospective cohort study. Blood samples of HCWs vaccinated with both ChAdOx1 doses over a period of 12 weeks were collected at weeks 4 and 8 post first vaccination and 2 weeks post second vaccination. Blood samples of HCWs vaccinated with BNT162b2 were collected in the third week after the first dose, and the second dose was then administered on the same day; two weeks post second dose (5 weeks after the first dose), blood samples were collected to assess the antibody response. The titers of anti-S antibodies against the severe acute respiratory syndrome coronavirus 2 spike (S) protein receptor-binding domain and the neutralizing antibodies in the collected blood were evaluated. RESULTS: Of the 309 HCWs enrolled in the study, 205 received ChAdOx1 and 104 received BNT162b2. Blood samples from participants receiving either the ChAdOx1 or BNT162b2 vaccine exhibited substantial anti-S and neutralizing antibody seropositivity subsequent to the second dose. All participants (100%) from both vaccine groups were seropositive for anti-S antibody, while 98% (201/205) of ChAdOx1-vaccinated individuals and 100% (104/104) of BNT162b2-vaccinated individuals were seropositive for neutralizing antibodies. The median levels of anti-S and neutralizing antibodies were significantly higher in the BNT162b2-vaccinated group than the ChAdOx1-vaccinated group; in particular, anti-S antibody titers of 1,020 (interquartile range, 571.0-1,631.0) U/mL vs. 2,360 (1,243-2,500) U/mL, P < 0.05, were recorded for the ChAdOx1 and BNT162b2 groups, respectively, and neutralizing antibody titers of 85.0 (65.9-92.1%) vs. 95.8 (94.4-96.6%), P < 0.05, were recorded for the ChAdOx1 and BNT162b2 groups, respectively. In the ChAdOx1 vaccine group, the neutralizing antibody level was significantly higher in women than in men (85.7 [70.3-92.5%] vs. 77.7 [59.2-91.0%], P < 0.05); however, the neutralizing antibody titer in the BNT162b2 vaccine group did not vary between the two sexes (95.9 [95.2-96.6%] vs. 95.2 [93.5-96.3%], P = 0.200). Analysis of the correlation of antibody profiles with age revealed that the levels of anti-S antibodies and signal inhibition rate (SIR) of neutralizing antibodies decreased significantly with age. CONCLUSION: Both the ChAdOx1- and BNT162b2-vaccinated groups showed high seropositivity for anti-S and neutralizing antibodies. The SIR of neutralizing antibodies in the ChAdOx1 vaccine group was higher in women than in men. Enhanced antibody responses were observed in participants vaccinated with BNT162b2 compared to those vaccinated with the ChAdOx1 vaccine.

Reactogenicity after the first and second doses of BNT162b2 mRNA coronavirus disease vaccine: a single-center study.

PURPOSE: This study was conducted to determine differences in adverse events associated with the first and second doses of the BNT162b2 coronavirus disease 2019 vaccine based on the age and sex of recipients. MATERIALS AND METHODS: An online survey on the post-vaccination adverse events of healthcare workers was conducted from March 2021 to April 2021. The differences in the types of adverse events, including severity, onset time, and duration of symptoms, and how the adverse events were dealt with by the patient were analyzed based on the age and sex. The profiles of adverse events were compared after the first and second vaccination doses. RESULTS: Among the 131 participants who participated in the online survey out of 208 vaccine recipients, 43 and 80 recipients of the BNT162b2 vaccine experienced adverse events after the first and second dose, respectively. No sex-related differences were observed in the profiles of adverse events in vaccinated recipients. The overall frequency of adverse events did not differ based on age after the first dose. After the second dose, the frequency of adverse events, including both local and systemic reactions was significantly higher in the younger age group than in the older age group. CONCLUSION: The BNT162b2 vaccine resulted in a higher frequency of adverse events after the second dose than after the first dose especially in the younger age group; however, no sex-related differences associated with these adverse events were observed.

Rapidly Declining SARS-CoV-2 Antibody Titers within 4 Months after BNT162b2 Vaccination.

The efficacy and safety of the BNT162b2 vaccine are known, but antibodies are expected to decrease over time after vaccination. We collected blood samples from 104 fully vaccinated health care workers at 3 and 5 weeks after first vaccination and 4 months after second vaccination. Antibody titers and neutralizing antibodies were measured. In our study, both antibody titers and neutralizing antibodies increased significantly at 5 weeks after first vaccination but decreased rapidly at 4 months after second vaccination. Additionally, the results showed a significant decrease regardless of gender or age. Further studies are needed to help determine the interval of SARS-CoV-2 vaccinations.

Report of the Korean Society of Infectious Diseases Roundtable Discussion on Responses to the Measles Outbreaks in Korea in 2019.

During the 2019 domestic measles outbreak in Korea, measles occurred in healthcare workers with two doses of the measles, mumps and rubella vaccine, and the strict application of the Occupational Safety and Health Act required medical institutions to identify healthcare workers' immunity to measles and vaccinate the susceptible pockets. In response to the frontline medical institutions' request to review the measles recommendations and guidelines, the Korean Society of Infectious Diseases held a roundtable discussion on the causes of measles outbreak, timing of vaccinations, antibody tests, and booster vaccinations for healthcare workers, and financial support from the government and municipality as well as response strategies against the outbreak in healthcare settings. In Korea, the seroprevalence of measles is decreasing in the vaccine-induced immunity group during the maintenance of measles elimination over several years. The susceptible group against measles is in their 20s and 30s, and this may be because of waning immunity rather than non-response considering Korea's vaccine policy. The risk of measles nosocomial infection from community increases as these susceptible pockets actively engage in medical institutions. Thus, data on the immunity of low seroprevalence group in Korea are needed, further discussion is needed on the booster vaccination based on the data. Especially, antibody testing and vaccination in healthcare workers may be necessary to prevent the spread of measles in medical insutitutions, and further discussion is needed regarding specific testing methods, and the timing and frequency of test and vaccination.

SARS-CoV-2 Antibody Response to the BNT162b2 mRNA Vaccine in Persons with Past Natural Infection.

There are still no agreed guidelines on the vaccination of coronavirus disease 2019 (COVID-19) for previously infected patients. Here, we present two seropositive healthcare workers (HCWs) working in an isolation ward who recovered from COVID-19 in April 2020 and got vaccinated with BNT162b2 vaccine in March 2021. We have assessed the clinical course, vaccine-related adverse events, and antibody response after natural infection and after first and second dose vaccination. One of the two HCWs was asymptomatic during quarantine, but the other had mild upper respiratory infection symptoms 1 day before admission, and the symptoms continued for 9 days. There was no pneumonic infiltration in chest X-ray in both patients, and no COVID-19 specific treatment was administered. Total immunoglobulin antibody and neutralizing antibody to anti-spike protein receptor-binding domain of severe acute respiratory syndrome coronavirus 2 were confirmed to be present in both HCWs in blood tests performed at 2 weeks and 4 weeks after discharge. Antibody response to mRNA vaccination showed marked elevation after the first vaccination, which was 30-40 times higher than that of antibody titer after natural infection in each patient (83.2 U/mL vs. > 2,500 U/mL in patient 1; 61.6 U/mL vs. > 2,500 U/mL in patient 2). Signal inhibition rate of neutralizing antibodies was also increased to over 97%. Due to this increased effect, there was little difference in antibody levels after the first and second dose. Both patients 1 and 2 suffered more from adverse vaccine reactions after the second vaccination than from COVID-19 symptoms.

Active-controlled phase III study of an egg-cultivated quadrivalent inactivated split-virion influenza vaccine (GC3110A) in healthy Korean children aged 6-35 months.

The inactivated trivalent influenza vaccine (TIV) offers limited protection when two influenza B lineages co-circulate or when there is a vaccine mismatch (i.e., discordance in the predominant circulating B strain and WHO-recommended B strain). Inactivated quadrivalent influenza vaccine (QIV) may reduce the burden of influenza. Here, we report the results of a phase 3 clinical trial that evaluated the immunogenicity and safety of a novel QIV, GC3110A, in Korean children aged 6-35 months, which has been approved and is currently in use in Korea. The study involved two parts. In Part 1, the safety of GC3110A was evaluated in 10 subjects. After none of the subjects reported grade 3 adverse events (AEs), we proceeded to Part 2. Part 2 was a randomized, double-blind, multicenter phase 3 trial wherein we compared the immunogenicity and safety of GC3110A with those of a licensed control TIV. Immunogenicity was evaluated by measuring hemagglutination inhibition titers. The 200 participants enrolled in Part 2 were randomized in a 4:1 ratio to receive GC3110A or control TIV. The study vaccine group met both primary (i.e., the lower limit of 95% confidence interval [CI] of the seroconversion rate exceeds 40% for four strains) and secondary (i.e., the lower limit of 95% CI of the seroprotection rate exceeds 70% for four strains) immunogenicity endpoints. There was no significant between-group difference in the seroconversion rate, seroprotection rate, and geometric mean titer for the shared strains. However, the study vaccine group demonstrated significantly higher immunity for the additional strain B/Yamagata. In the safety analysis, there was no significant between-group difference in the proportion of participants with solicited local AEs, solicited systemic AEs, and unsolicited AEs. In conclusion, the results indicate that GC3110A has comparable immunogenicity and safety to those of TIV. Clinical Trial Registry Number: NCT03285997.

Erratum: Addition of a Co-Author: Etiology of Invasive Bacterial Infections in Immunocompetent Children in Korea (2006-2010): a Retrospective Multicenter Study.

This corrects the article on e45 in vol. 33, PMID: 29349940.

Genetic structures of invasive Streptococcus pneumoniae isolates from Korean children obtained between 1995 and 2013.

BACKGROUND: Understanding the population genetics of pneumococci will allow detection of changes in the prevalence of circulating genotypes and evidence for capsular switching. We aimed to analyze the genetic structure of invasive pneumococcal isolates obtained from children before and after the use of pneumococcal conjugate vaccines (PCVs) in Korea. METHODS: A total of 285 invasive pneumococcal isolates were analyzed using serotyping, multilocus sequence typing, and antimicrobial susceptibility testing. We classified the isolation year to pre-PCV7 (1995-2003; n = 70), post-PCV7 (2004-2010; n = 142), and post-PCV13 (2011-2013; n = 73) periods. RESULTS: Of the 10 clonal complexes (CCs), antibiotic-resistant international clones, CC320 (31.6%), CC81 (14.7%), and CC166 (6.7%) were the main complexes. Serotype 19A was the main serotype of CC320 throughout the periods. Serotypes of CC81 mainly comprised of 23F (53.3%) in pre-PCV7 period and replaced by non-vaccine types (NVTs; 6C [10%], 13 [30%], 15A [40%], and 15B/C [20%]) in post-PCV13 period. The main serotype responsible for CC166 also changed from 9 V (80%) in pre-PCV7 to NVT 11A (50%) in post-PCV13 periods. Non-susceptibility to penicillin (42.3%) was the highest in CC320, increasing from 0 to 76%. CONCLUSION: The genetic structures of invasive pneumococcal isolates in Korean children have changed concomitantly with serotype after the implementation of PCVs.

Etiology of Invasive Bacterial Infections in Immunocompetent Children in Korea (2006-2010): a Retrospective Multicenter Study.

BACKGROUND: Invasive bacterial infections in apparently immunocompetent children were retrospectively analyzed to figure causative bacterial organisms in Korea. METHODS: A total of 947 cases from 25 university hospitals were identified from 2006 to 2010 as a continuance of a previous 10-year period study from 1996 to 2005. RESULTS: Escherichia coli (41.3%), Streptococcus agalactiae (27.7%), and Staphylococcus aureus (27.1%) were the most common pathogens in infants < 3 months of age. S. agalactiae was the most prevalent cause of meningitis and pneumonia and E. coli was the major cause of bacteremia without localizing signs in this group. In children 3 to 59 months of age, Streptococcus pneumoniae (54.2%), S. aureus (20.5%), and Salmonella spp. (14.4%) were the most common pathogens. S. pneumoniae was the leading cause of pneumonia (86.0%), meningitis (65.0%), and bacteremia without localizing signs (49.0%) in this group. In children ≥ 5 years of age, S. aureus (62.8%) was the predominant pathogen, followed by Salmonella species (12.4%) and S. pneumoniae (11.5%). Salmonella species (43.0%) was the most common cause of bacteremia without localizing signs in this group. The relative proportion of S. aureus increased significantly over the 15-year period (1996-2010) in children ≥ 3 months of age (P < 0.001), while that of Haemophilus influenzae decreased significantly in both < 3 months of age group (P = 0.036) and ≥ 3 months of age groups (P < 0.001). CONCLUSION: S. agalactiae, E. coli, S. pneumoniae, and S. aureus are common etiologic agents of invasive bacterial infections in Korean children.

Early Changes in the Serotype Distribution of Invasive Pneumococcal Isolates from Children after the Introduction of Extended-valent Pneumococcal Conjugate Vaccines in Korea, 2011-2013.

This study was performed to measure early changes in the serotype distribution of pneumococci isolated from children with invasive disease during the 3-year period following the introduction of 10- and 13-valent pneumococcal conjugate vaccines (PCVs) in Korea. From January 2011 to December 2013 at 25 hospitals located throughout Korea, pneumococci were isolated among children who had invasive pneumococcal disease (IPD). Serotypes were determined using the Quellung reaction, and the change in serotype distribution was analyzed. Seventy-five cases of IPD were included. Eighty percent of patients were aged 3-59 months, and 32% had a comorbidity that increased the risk of pneumococcal infection. The most common serotypes were 19A (32.0%), 10A (8.0%), and 15C (6.7%). The PCV7 serotypes (4, 6B, 9V, 14, 18C, 19F, 23F, and 6A) accounted for 14.7% of the total isolates and the PCV13 minus PCV7 types (1, 3, 5, 7F and 19A) accounted for 32.0% of the total isolates. Serotype 19A was the only serotype in the PCV13 minus PCV7 group. The proportion of serotype 19A showed decreasing tendency from 37.5% in 2011 to 22.2% in 2013 (P = 0.309), while the proportion of non-PCV13 types showed increasing tendency from 45.8% in 2011 to 72.2% in 2013 (P = 0.108). Shortly after the introduction of extended-valent PCVs in Korea, serotype 19A continued to be the most common serotype causing IPD in children. Subsequently, the proportion of 19A decreased, and non-vaccine serotypes emerged as an important cause of IPD. The impact of extended-valent vaccines must be continuously monitored.

Safety and immunogenicity of a single dose of a quadrivalent meningococcal conjugate vaccine (MenACYW-D): a multicenter, blind-observer, randomized, phase III clinical trial in the Republic of Korea.

OBJECTIVES: To assess the safety and immunogenicity of a meningococcal polysaccharide diphtheria toxoid conjugate vaccine (MenACYW-D) in a Korean population. METHODS: This was a phase III, blind-observer, controlled study in which participants aged 11-55 years were randomized (2:1 ratio) to a single dose of MenACYW-D or tetanus/diphtheria/acellular pertussis (Tdap) vaccine. Outcomes included rates of seroconversion against all serogroups (≥4-fold increase in antibody titer from pre-vaccination), geometric mean titers (GMTs) at days 0 and 28 based on a serum bactericidal assay using baby rabbit complement, rates of seroprotection (titer ≥1:128) at day 28, and safety. RESULTS: A total of 300 participants were enrolled in the study (200 MenACYW-D and 100 Tdap). Seroconversion rates for serogroups A, C, Y, and W-135 were 77.8%, 88.3%, 74.6%, and 92.4%, respectively, for the MenACYW-D group and 9.3%, 8.1%, 12.2%, and 8.2%, respectively, for the Tdap group. The proportions of participants with pre-vaccination titers ≥1:128 were 57.3%, 12.6%, 51.5%, and 22.2% for serogroups A, C, Y, and W-135, respectively; post-vaccination rates were 98.5%, 89.4%, 96.0%, and 95.0% for the MenACYW-D group. A lower proportion of participants reported solicited reactions with MenACYW-D (46.2%) compared with Tdap (76.8%). CONCLUSION: A single dose of MenACYW-D was well tolerated and elicited a robust immune response in Korean adolescents and adults.

Varicella and varicella vaccination in South Korea.

With continuing occurrence of varicella despite increasing vaccine coverage for the past 20 years, a case-based study, a case-control study, and an immunogenicity and safety study were conducted to address the impact of varicella vaccination in South Korea. Varicella patients under the age of 16 years were enrolled for the case-based study. For the case-control study, varicella patients between 12 months and 15 years of age were enrolled with one control matched for each patient. For the immunogenicity and safety study, otherwise healthy children from 12 to 24 months old were immunized with Suduvax (Green Cross, South Korea). Fluorescent antibody to membrane antigen (FAMA) varicella-zoster virus (VZV) antibody was measured before and 6 weeks after immunization. In the case-based study, the median age of the patients was 4 years. Among 152 patients between 1 and 15 years of age, 139 children received varicella vaccine and all had breakthrough infections. Clinical courses were not ameliorated in vaccinated patients, but more vaccinated patients received outpatient rather than inpatient care. In the case-control study, the adjusted overall effectiveness of varicella vaccination was 54%. In the immunogenicity and safety study, the seroconversion rate and geometric mean titer for FAMA antibody were 76.67% and 5.31. Even with increasing varicella vaccine uptake, we illustrate no upward age shift in the peak incidence, a high proportion of breakthrough disease, almost no amelioration in disease presentation by vaccination, and insufficient immunogenicity of domestic varicella vaccine. There is need to improve the varicella vaccine used in South Korea.

Immunogenicity, reactogenicity and safety of a human rotavirus vaccine (RIX4414) in Korean infants: a randomized, double-blind, placebo-controlled, phase IV study.

Rotavirus (RV) infection is the primary cause for childhood gastroenteritis worldwide. In Korea, RV infection is most common among children less than 5 years of age. This post-licensure study was conducted to further evaluate the RV vaccine (RIX4414) to provide additional local clinical data to the Korean Food and Drug Association. Healthy infants aged 6-12 weeks were enrolled to receive two doses of either RIX4414 or placebo as per 0, 1-2 month schedule. Blood samples were collected before dose-1 and one month post-dose-2 of RIX4414/placebo to assess serum anti-RV IgA antibody concentrations using ELISA. Gastroenteritis stool samples were tested for the presence of RV using ELISA. RV positive samples were subjected to further analysis for G and P typing. Among 684 infants enrolled and vaccinated, 432 infants (RIX4414=318; placebo=114) were included in the according-to-protocol cohort for immunogenicity. The anti-RV IgA antibody seroconversion rates in the RIX4414 group following one month post-dose-2 were 88.1% (95% CI: 84.0-91.4) and the corresponding geometric mean concentration in the RIX4414 group was 208.5 U/ml (95% CI: 174.2-249.5). Occurrence of solicited and unsolicited adverse events were similar in both, RIX4414 and placebo groups. None of the gastroenteritis stool samples tested positive for RV and no fatal SAEs were reported in either groups. The two-dose regimen of RIX4414 was observed to be immunogenic with a similar safety profile as compared to the placebo group, when administered to healthy Korean infants.

Response to primary and booster vaccination with 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine in Korean infants.

BACKGROUND: This randomized single-blind study in Korea evaluated noninferiority of the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) versus the 7-valent pneumococcal conjugate vaccine (7vCRM) when both were coadministered with H. influenzae type b (Hib) conjugate vaccine, as opposed to coadministration with diphtheria-tetanus-acellular pertussis-based combination vaccines in previous studies. METHODS: Infants received 3 primary doses at 2, 4, and 6 months and a booster dose at 12 to 18 months of PHiD-CV (N = 374) or 7vCRM (N = 129), both coadministered with Hib vaccine. Immune responses were measured 1 month postdose 3 and postbooster using 22F-inhibition enzyme-linked immunosorbent assay and functional opsonophagocytic activity assay. RESULTS: PHiD-CV-induced antibody responses against each of the vaccine pneumococcal serotypes and protein D. Noninferiority to 7vCRM was demonstrated for all 10 PHiD-CV serotypes in terms of percentages of subjects reaching an antibody concentration ≥0.2 µg/mL after primary vaccination. Postprimary and postbooster, percentages of subjects with antibody concentration ≥0.2 µg/mL or opsonophagocytic activity titer ≥8 were generally consistent between groups for each pneumococcal serotype common to both vaccines. The safety and reactogenicity profiles of PHiD-CV and 7vCRM were generally comparable after both primary and booster vaccination. CONCLUSIONS: In this Korean study, 3-dose PHiD-CV priming followed by a booster dose was immunogenic for all 10 vaccine pneumococcal serotypes and protein D. Noninferiority to 7vCRM in terms of enzyme-linked immunosorbent assay threshold responses postpriming was demonstrated. The safety and reactogenicity profiles of both vaccines when coadministered with Hib vaccine were generally comparable.

Etiology of invasive bacterial infections in immunocompetent children in Korea (1996-2005): a retrospective multicenter study.

The purpose of this study was to identify the major etiological agents responsible for invasive bacterial infections in immunocompetent Korean children. We retrospectively surveyed invasive bacterial infections in immunocompetent children caused by eight major pediatric bacteria, namely Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pyogenes, Listeria monocytogenes, and Salmonella species that were diagnosed at 18 university hospitals from 1996 to 2005. A total of 768 cases were identified. S. agalactiae (48.1%) and S. aureus (37.2%) were the most common pathogens in infants younger than 3 months. S. agalactiae was a common cause of meningitis (73.0%), bacteremia without localization (34.0%), and arthritis (50%) in this age group. S. pneumoniae (45.3%) and H. influenzae (20.4%) were common in children aged 3 months to 5 yr. S. pneumoniae was a common cause of meningitis (41.6%), bacteremia without localization (40.0%), and bacteremic pneumonia (74.1%) in this age group. S. aureus (50.6%), Salmonella species (16.9%), and S. pneumoniae (16.3%) were common in older children. A significant decline in H. influenzae infections over the last 10 yr was noted. S. agalactiae, S. pneumoniae, and S. aureus are important pathogens responsible for invasive bacterial infections in Korean children.

Current status and clinical presentations of invasive neonatal Group B streptococcal infections in Korea.

BACKGROUND: Group B streptococcus (GBS) is the most common cause of invasive neonatal infections in developed countries. The incidence of early-onset GBS disease in Korea is known to be much lower than that in other developed countries; however neonatal GBS disease has been frequently reported in recent years in Korea. This retrospective study sought to determine the current status and clinical presentation of neonatal GBS disease in Korea. METHODS: From January 1996 through December 2005, GBS cases (n= 157) diagnosed in blood, cerebrospinal fluid, or other sterile body fluids among infants <3 months of age from 14 university hospitals in Korea were identified. Age of onset, diagnosis, underlying medical conditions, and outcomes were investigated by reviewing the medical records. RESULTS: A total of 157 cases were identified during the study period. Of the cases, 32 were early-onset disease (EOD) and 125 were late-onset disease (LOD). Twenty-six of the EOD cases had symptoms during the first 24 h after birth. One hundred of the 157 GBS cases were diagnosed as meningitis. The mortality rate of EOD was 20.7%. The case fatality rate of LOD was 7.2% and 25.2% of LOD cases had sequelae. CONCLUSIONS: GBS is becoming an important cause of invasive neonatal infections in Korea, with LOD being more common. It may not be currently necessary to adopt the prevention guidelines of perinatal GBS disease in Korea. However, studies of maternal GBS carriage rates and neonatal GBS disease will continue.

The causative organisms of bacterial meningitis in Korean children in 1996-2005.

Bacterial meningitis remains a serious cause of morbidity and mortality in childhood, despite the availability of effective vaccines against Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae. The purpose of this study was to analyze data on bacterial meningitis cases in Korea from 1996 through 2005. The information of all hospitalized bacteria-proven meningitis cases was obtained from 17 university hospitals nationwide. A total of 402 cases were identified. Of these, 125 (29.9%) cases were neonates. Streptococcus agalactiae was the most common bacteria responsible for 99 (24.6%) of all cases regardless of age, followed by S. pneumoniae for 91 (22.6%) and H. influenzae for 67 (16.7%) patients. The common etiology beyond the neonatal period was S. pneumoniae for 91 (33.0%) followed by H. influenzae for 63 (22.8%) patients. The overall case fatality rate was 9.4%, which was similar with that in 1986-1995. In conclusion, S. agalactiae, S. pneumoniae and H. influenzae were important etiologic agents of bacterial meningitis in children in the last 10 yrs. It is required to establish the preventive strategy of the three bacteria. The nationwide epidemiologic study should be continued to evaluate immunization strategy and efficacy.