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Published on: November 10, 2023
Transmissibility of SARS-CoV-2 Variants as a Secondary Attack in Thai Households: a Retrospective Study
Natcha Watanapokasin1, Taweegrit Siripongboonsitti2, Teerapat Ungtrakul1
1Faculty of Medicine and Public Health, HRH Princess Chulabhorn College of Medical Science, Chulabhorn Royal Academy, Bangkok, Thailand.
Objective:
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads through person-to-person contact via small droplet particles, especially in poorly ventilated indoor settings such as households, estimating at 16.6% of secondary attack rate. This study aimed to explore the secondary attack rate in Thai households during the new SARS-CoV-2 variant outbreak.
Methods:
We obtained a retrospective study of exposed members in households among 30 sets of patients with reverse transcriptase-polymerase chain reaction (RT-PCR) confirmed SARS-CoV-2 infection (index cases) at Chulabhorn Hospital, Bangkok, Thailand, from May 1 to June 30, 2021. Characteristic of index cases and households were extracted from medical records and analyzed.
Results:
The 30 index cases were associated with 157 exposed household close contacts. Seventy-six were RT-PCR confirmed SARS-CoV-2 infections within 14 days after being exposed from an index case, with a secondary attack rate of 48%. However, there was no difference between secondary attack rates among the age of contact, household size, or SARS-CoV-2 variants.
Conclusion:
Our data show high transmissibility of SARS-CoV-2, which was notably exaggerated compared to previous studies. Therefore, developing preventive strategies such as post-exposure prophylaxis (PEP) in close contact with SARS-CoV-2 infection would be a novel supplement to the current standard of care.
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