Widespread Household Transmission of SARS-CoV-2 B.1.1.529 (Omicron) Variant from Children in South Korea 2022

The study, “Widespread Household Transmission of SARS-CoV-2 B.1.1.529 (Omicron) Variant from Children in South Korea 2022” published in the Yonsei Medical Journal, provides insights into the transmission dynamics of the Omicron variant of SARS-CoV-2, particularly focusing on the role of children in spreading the virus within households.

Key Findings of the Study:

  1. Outbreak Origin: The outbreak began with young children attending various pediatric facilities, leading to extensive household transmission affecting 75 families with 88 confirmed cases within three weeks. The outbreak was first identified in a 10-year-old child who had visited a childcare center and a Taekwondo academy​​​​.
  2. Transmission Dynamics: Extensive contact tracing revealed widespread transmission in multiple pediatric facilities and families. Frequent and intimate interactions among children, combined with inadequate indoor ventilation in pediatric facilities, were common factors in the spread of the virus​​.
  3. Case-Patient Profile: Of the 201 confirmed case-patients, 55.2% of transmissions occurred in households. The most affected age group was children under 10 years, accounting for 34.3% of all cases. The most common symptoms were fever, sore throat, cough, sputum production, and runny or stuffy nose. No critical illnesses or deaths were reported​​.
  4. Secondary Attack Rate (SAR): The overall SAR in households was 42.1%. The highest SAR was observed in households with an index patient aged 0 to 9 years. Vaccinated index case-patients showed a lower SAR compared to unvaccinated individuals. The SAR from symptomatic index case-patients was higher than from asymptomatic ones​​.
  5. Transmission Rate Comparison: The SAR of the Omicron variant in households was higher than that of the wild-type or Delta variant, consistent with other studies on Omicron household transmission. The higher infectiousness in unvaccinated children and their close interaction patterns contributed to this elevated SAR​​.
  6. Study Limitations: The study’s limitations included the lack of phylogenetic or sub-lineage analysis for the Omicron variant, as sequencing was conducted only for selected case-patients. The small sample size for certain SARs and lack of accounting for various risk factors of transmission limited the generalizability of the findings. No clear distinction was made between secondary and potential tertiary case-patients within households​​.

Summary for Blog Post:

This study provides significant insights into the transmission dynamics of the Omicron variant of SARS-CoV-2, with a particular focus on the role of children. The outbreak in South Korea highlights the substantial role children play in spreading the virus within households, especially in pediatric settings like schools and academies. The study shows a high secondary attack rate in households, particularly involving young, unvaccinated children. These findings underscore the need for tailored public health measures directed towards children and pediatric facilities to mitigate the spread of COVID-19. The study also emphasizes the importance of multi-pronged prevention measures, including improved indoor ventilation, mask-wearing, and vaccination, to control the spread of the virus within communities. Despite its limitations, this study contributes to the understanding of the Omicron variant’s transmission patterns and the critical role of children in the spread of COVID-19.

Read More: https://eymj.org/DOIx.php?id=10.3349/ymj.2022.0608

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