Publications by authors named "Hee-Jin Cheong"

Influenza C virus (ICV) was discovered in 1947 and detected in humans, with natural infections occurring periodically. However, early studies on ICV were challenging in diagnosis because the virus is difficult to culture. As a result, the disease burden and pathogenicity of ICV have been underestimated.

View Article and Find Full Text PDF

After the transition of coronavirus disease 2019 (COVID-19) from a pandemic to an endemic phase, data on respiratory viral infections remain limited. This study compared the clinical outcomes of SARS-CoV-2, influenza virus (INFV), and respiratory syncytial virus (RSV) infections and investigated how underlying medical conditions influence disease severity. During Omicron subvariant dominant periods, we conducted a multicenter, retrospective cohort study including laboratory-confirmed cases of SARS-CoV-2, INFV, and RSV infections in hospitalized patients aged ≥ 19 years.

View Article and Find Full Text PDF

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to evolve, with each new strain becoming immunologically distinct from previous strains. The updated vaccine formulation for the 2023/24 season contained the mRNA of the XBB.1.

View Article and Find Full Text PDF

South Korea's current vaccination policies leave a surveillance gap for non-National Immunization Program (NIP) vaccines. In this study, we proposed a sentinel surveillance approach for monitoring the safety of non-NIP vaccines. Vaccination data were collected retrospectively among patients hospitalized with pre-defined adverse events of special interest (AESI) by reviewing electronic medical records in five university hospitals.

View Article and Find Full Text PDF

Background: During the 2023-2024 season, the influenza epidemic in South Korea peaked earlier, and the influenza vaccination rate among individuals aged ≥ 65 was high (82.2%). However, data on real-world vaccine effectiveness against influenza are lacking.

View Article and Find Full Text PDF

AdCLD-CoV19-1, a chimeric adenovirus-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine, was previously reported to elicit robust antibody responses in mice and non-human primates after a single dose. In this study, we conducted a systems serology analysis to investigate changes in humoral immune responses induced by varying doses of the AdCLD-CoV19-1 vaccine in a phase I clinical trial. Serum samples from participants receiving either a low or a high dose of the vaccine were analyzed for antibody features against prototype SARS-CoV-2 spike (S) domains (full-length S, S1, S2, and receptor binding domain), as well as Fc receptor binding and effector functions.

View Article and Find Full Text PDF

Introduction: Coronavirus 2019 (COVID-19) vaccination rates in pregnant women remain low owing to safety concerns. When evaluating vaccine safety, comparisons with unvaccinated individuals may lead to healthy vaccinee bias. This study aimed to investigate the association between mRNA-based COVID-19 vaccination and pregnancy-related adverse outcomes compared with influenza vaccination.

View Article and Find Full Text PDF
Article Synopsis
  • - Influenza poses a considerable healthcare challenge in Korea, prompting the government to start a national vaccination initiative; previous research on vaccine effectiveness (VE) focused only on single seasons.
  • - A study from 2011 to 2021 involving over 5,000 older adults showed that the effectiveness of the flu vaccine varied significantly by season, with only 3 out of 9 seasons achieving a >70% match between the vaccine and circulating strains.
  • - The analysis found that vaccination lowered flu-related hospitalizations by 13.6%, highlighting that when the vaccine strains matched circulating strains, the VE was notably better, at 28.8%, compared to -12.0% in mismatched seasons.
View Article and Find Full Text PDF
Article Synopsis
  • SARS-CoV-2 vaccines are essential for fighting COVID-19; however, decreasing antibody levels after vaccination create challenges for long-term immunity and herd protection.
  • A study involving 44 adults who received different COVID-19 vaccines revealed that specific gut bacteria, like Faecalibacterium prausnitzii and Escherichia coli, influence how long vaccine-induced antibodies last and how quickly they decline.
  • These results suggest that the gut microbiome might play a crucial role in sustaining vaccine effectiveness, indicating that strategies targeting gut bacteria could help improve vaccine responses.
View Article and Find Full Text PDF

Carbapenem-resistant Acinetobacter baumannii (CRAB) pneumonia has been a serious problem in the intensive care unit (ICU). However, defined characteristics of respiratory microbiome in CRAB pneumonia are lacking nowadays. This study aimed to analyze respiratory microbiome of CRAB pneumonia compared to non-CRAB pneumonia and reveal the clinical significance of respiratory microbiome data in these patients.

View Article and Find Full Text PDF
Article Synopsis
  • The Korean Society of Infectious Diseases has been updating adult immunization guidelines since 2007, with major revisions made for seven vaccines in 2023.
  • Key changes include enhanced influenza vaccines for the elderly, the introduction of a recombinant herpes zoster vaccine, and updates on pneumococcal vaccine options.
  • Other notable adjustments involve extending the HPV vaccine eligibility age, adding recommendations for meningococcal B vaccine, and altering pre-exposure rabies vaccine doses, while older guidelines remain for unmentioned vaccines.
View Article and Find Full Text PDF
Article Synopsis
  • Erythema nodosum (EN) is a painful skin condition known for its tender nodules and is typically self-limiting, with few cases linked to SARS-CoV-2 vaccination reported.
  • A unique case involved a 63-year-old woman whose EN lasted over three months after COVID-19, proving resistant to standard treatments but improving with high-dose steroids and NSAIDs.
  • This case highlights the potential for EN as a skin manifestation of Long COVID, suggesting that immune dysregulation from lingering coronavirus effects can lead to persistent symptoms.
View Article and Find Full Text PDF

Recently, respiratory syncytial virus (RSV) vaccines based on the prefusion F (pre-F) antigen were approved in the United States. We aimed to develop an enzyme-linked immunosorbent assay (ELISA)-based protocol for the practical and large-scale evaluation of RSV vaccines. Two modified pre-F proteins (DS-Cav1 and SC-TM) were produced by genetic recombination and replication using an adenoviral vector.

View Article and Find Full Text PDF
Article Synopsis
  • The COVID-19 virus is evolving into an endemic disease, prompting updates in vaccine formulations to target the XBB.1.5 strain specifically.
  • A multicenter study analyzed the effectiveness of the XBB.1.5 monovalent vaccine, revealing that vaccinated individuals were less likely to contract COVID-19 than unvaccinated individuals.
  • The interim results showed a vaccine effectiveness of 56.8%, indicating significant protection against COVID-19 for one to two months post-vaccination.
View Article and Find Full Text PDF
Article Synopsis
  • * The primary goal of vaccination is to decrease severe illness and death rather than completely eliminate the virus.
  • * Proposed strategies for COVID-19 vaccination focus on targeting high-risk individuals, aligning with seasonal influenza vaccinations, and encouraging co-administration of both vaccines to boost overall coverage.
View Article and Find Full Text PDF
Article Synopsis
  • - This study analyzed the presence of RSV antibodies in 150 blood samples from individuals across different age groups, collected between June and September 2021.
  • - Results showed low antibody levels for RSV, particularly in young children and older adults, who are typically at a higher risk for severe infections.
  • - The findings highlight the need for RSV vaccination, especially for pregnant women and individuals over 60, due to the high disease burden and low immunity in these groups.
View Article and Find Full Text PDF
Article Synopsis
  • This study assessed long-term immunity in adults who received the BA.4/5 bivalent COVID-19 vaccine, focusing on both antibody and T-cell responses.
  • Participants showed significant increases in anti-binding domain IgG and neutralizing antibodies (NAb) against certain Omicron variants by 9 months post-vaccination.
  • The T-cell responses were robust and cross-reactive for both previously infected and SARS-CoV-2-naïve individuals, although there was minimal increase after vaccination.
View Article and Find Full Text PDF
Article Synopsis
  • The 2023-2024 influenza season in South Korea saw an earlier peak compared to previous years, prompting a study on vaccine effectiveness.
  • Researchers enrolled 2,632 individuals with influenza-like symptoms from eight hospitals to assess interim vaccine effectiveness from November 1 to December 31, 2023.
  • The study found an overall adjusted vaccine effectiveness of 22.5% for the general population, with specific rates of 22.3% for influenza A and 9.4% for influenza A/H1N1.
View Article and Find Full Text PDF
Article Synopsis
  • - The study examined the durability of immunity following the third dose of COVID-19 vaccines in 94 healthy adults, finding that antibody levels remained significantly higher even 9-12 months later compared to levels after the second dose.
  • - Anti-spike IgG antibody responses peaked after the third dose but gradually decreased over time; however, breakthrough infections during the Omicron period increased neutralizing antibodies against various strains.
  • - The results suggest that the mRNA vaccine booster leads to lasting humoral immunity for at least a year and maintains T-cell immunity, indicating the potential for an annual COVID-19 vaccination approach.
View Article and Find Full Text PDF
Article Synopsis
  • - In Korea, there is currently no surveillance for vaccines outside the national immunization program (NIP), and adult vaccine safety monitoring is insufficient, prompting the need for a new safety monitoring system for non-NIP vaccines.
  • - The study involved monitoring the safety of four non-NIP vaccines (Tdap, PCV13, ZVL, and RZV) by collecting data on adverse events through questionnaires sent to individuals after vaccination at various healthcare institutions.
  • - Results showed high response rates for monitoring, with 555 identified adverse events over 10 months, leading to the establishment of a safety system that requires ongoing government support for effectiveness and improvement.
View Article and Find Full Text PDF

Background: Bivalent booster mRNA vaccines containing the omicron-variant strains have been introduced worldwide in the autumn of 2022. Nevertheless, the omicron subvariants evoked another large coronavirus disease 2019 (COVID-19) pandemic wave in late 2022 and early 2023.

Methods: A retrospective, test-negative, case-control study was conducted to estimate the vaccine effectiveness (VE) of bivalent COVID-19 vaccines in 8 university hospitals between January and February 2023.

View Article and Find Full Text PDF
Article Synopsis
  • * Methods: A clinical trial was conducted with 154 healthy adults who received either both vaccines at the same time or separately, with follow-ups for adverse events and immune response assessments over six months.
  • * Results: While the combined vaccine group showed slightly lower overall antibody response rates for some coronavirus strains compared to the separate vaccine group, it produced a stronger neutralizing antibody response against the Omicron variant, with mostly mild side effects reported in both groups.
View Article and Find Full Text PDF
Article Synopsis
  • Research on a bivalent mRNA vaccine containing BA.4/5 reveals its effectiveness in boosting neutralizing antibodies (nAbs) against both the original SARS-CoV-2 and Omicron subvariants BN.1 and XBB.1.5.
  • A study involving 40 individuals showed that those previously infected with SARS-CoV-2 had significantly higher nAb levels post-vaccination compared to those without prior infection.
  • The findings indicate that ongoing development of vaccines targeting specific emerging variants like XBB.1.5 may be crucial for improving protection against COVID-19, particularly for high-risk populations.
View Article and Find Full Text PDF
Article Synopsis
  • - The study aimed to compare the occurrence of adverse events of special interest (AESIs) between two types of COVID-19 vaccines: adenoviral vector-based (ChAdOx1) and mRNA-based (BNT162b2 or mRNA-1273).
  • - Researchers analyzed data from the National Health Insurance Service database, finding that both vaccine types had low incidences of AESIs, but noted higher rates of certain heart-related issues in those who received mRNA vaccines.
  • - Key findings highlighted significant differences in safety profiles between the two vaccine platforms, especially regarding myocarditis and Guillain-Barré syndrome, while overall adverse event risks were low for both.
View Article and Find Full Text PDF