The incidence and clinical characteristics of myocarditis and pericarditis following mRNA-based COVID-19 vaccination in Republic of Korea adolescents from July 2021 to September 2022

Objectives@#Age-specific information regarding myocarditis/pericarditis in adolescents following mRNA-based coronavirus disease 2019 (COVID-19) vaccination in Asia remains insufficient. This study investigated the incidence and clinical characteristics of myocarditis/pericarditis in Republic of Korea adolescents after mRNA-based COVID-19 vaccination. @*Methods@#This retrospective descriptive study utilized patient data from the Korea Immunization Management System. Incidence rates were calculated according to age and sex. Clinical characteristics (symptoms/signs, laboratory values, and imaging results) were compared between mild and severe cases. @*Results@#Between July 19, 2021 and September 30, 2022, 3,728,224 individuals aged 12 to 19 years received 6,484,165 mRNA-based COVID-19 vaccines, and 173 cases met the case definition for myocarditis/pericarditis: 151 mild (87.3%) and 22 severe (12.7%). The incidence was 3.8-fold higher in males than in females. Troponin I/troponin T was elevated in 96% of myocarditis cases, demonstrating higher sensitivity than creatine kinase-myocardial band (67.6%) or C-reactive protein (75.2%). ST-segment or Twave on electrography abnormalities were found in 60.3% (85/141). Paroxysmal/sustained atrial/ventricular arrhythmias were more common in severe than in mild cases (45.5% vs. 16.8%, p=0.008). Edema on T2-weighted magnetic imaging occurred in 21.6% (8/37) and 62.5% (5/8) of mild and severe cases, respectively (p=0.03). Abnormal pericardial fluid collection or pericardial inflammation was found in 75.4% of pericarditis cases (49/65). @*Conclusion@#Myocarditis/pericarditis occurred in rare cases following mRNA-based COVID-19 vaccination. Most cases were mild, but the incidence was higher in adolescent males and after the second dose. As bivalent severe acute respiratory syndrome coronavirus 2 mRNA vaccination started in South Korea in October 2022, the post-vaccination incidence of myocarditis/pericarditis should be closely monitored, considering clinical characteristics.

Evaluation of Timeliness of Palivizumab Immunoprophylaxis Based on the Epidemic Period of Respiratory Syncytial Virus: 22 Year Experience in a Single Center

PURPOSE: This study aimed to analyze the epidemic period of RSV infection and evaluate the appropriate time of palivizumab immunoprophylaxis. METHODS: From January 1991 to July 2012, nasopharyngeal (NP) aspirates were obtained from patients who visited Seoul National University Children's Hospital for respiratory symptoms. NP samples were used to detect respiratory viruses. Among them, we analyzed the positive number and detection rate of RSV infection in two-week interval. The beginning of RSV season was defined when RSV positive number was more than 4 and RSV detection rate was over 10%. From January 2007 to March 2014, we analyzed the starting time of palivizumab immunoprophylaxis for the infants at high risk. RESULTS: The RSV detection rate was 2,013/21,698 (9.69%) over 22 years. The median RSV season was from 2nd-3rd week of October to 1st- 2nd week of February. The earliest starting week was the 3rd week of July in year 2001, and the latest end week was the 3rd week of May in year 1990. Palivizumab immunoprophylaxis was initiated most frequently at the 3rd week of October (18.7%). However, the percentage of starting palivizumab on the 1st week of September has increased from 3.8% in the year 2007 to 14.1% in 2013. CONCLUSIONS: The year to year variability of RSV season exists. The starting time of palivizumab immunoprophylaxis should be adjusted based on the season of RSV epidemic.

Severe Anemia Due to Parvovirus Infection Following Treatment with Rituximab in a Pediatric Kidney Transplant Recipient: Anemia after Treatment of Rituximab in Kidney Recipient Patient

Rituximab (RTX), a monoclonal antibody against the B-cell marker CD20, is commonly used as a treatment for antibody-mediated diseases or B-lymphocyte-mediated diseases. Destruction of B cells may reverse the disease course in many conditions; however, patients who are treated with RTX cannot respond appropriately to de novo infection due to lack of B lymphocytes. Here, we report one such case. A 7-year-old renal allograft recipient presented with severe anemia due to parvovirus infection after RTX treatment. The patient had focal segmental glomerulosclerosis and had received cadaveric kidney transplantation 6 months previously. She was treated with high-dose steroid for acute rejection and RTX for Epstein Barr Virus infection 3 months previously. At presentation, her hemoglobin level was 5.4 g/dL and leukocyte and platelet counts were normal. She had microcytic normochromic anemia and high viral load of parvovirus B19(70,578 copies/mL). Intravenous immunoglobulin (200 mg/kg.d) treatment controlled the progression of anemia and parvovirus infection. De novo parvovirus infection during the B lymphocyte-depletion period may have precipitated the severe anemia in this case. Close monitoring of infection is required after RTX therapy.