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Volume 27, Number 12—December 2021
Research Letter

Limited and Short-Lasting Virus Neutralizing Titers Induced by Inactivated SARS-CoV-2 Vaccine

Taweewun Hunsawong, Stefan Fernandez, Rome Buathong, Naretrit Khadthasrima, Kamonthip Rungrojchareonkit, Jindarat Lohachanakul, Rungarun Suthangkornkul, Kedsara Tayong, Angkana T. Huang, Chonticha Klungthong, Piyawan Chinnawirotpisan, Yongyuth Poolpanichupatam, Anthony R. Jones, Eric D. Lombardini, Supaporn Wacharapluesadee, and Opass PutcharoenComments to Author 
Author affiliations: Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand (T. Hunsawong, S. Fernandez, K. Rungrojchareonkit, J. Lohachanakul, R. Suthangkornkul, K. Tayong, A.T. Huang, C. Klungthong, P. Chinnawirotpisan, Y. Poolpanichupatam, A.R. Jones, E.D. Lombardini); Ministry of Public Health, Nonthaburi, Thailand (R. Buathong); Ministry of Public Health, Samut Sakhon Province, Samut Sakhon, Thailand (N. Khadthasrima); Thai Red Cross Emerging Infectious Diseases Clinical Center, Bangkok (S. Wacharapluesadee); Chulalongkorn University Faculty of Medicine, Bangkok (O. Putcharoen)

Main Article


Results of in vitro testing by surrogate virus neutralization test ELISA and microneutralization assay of CoronaVac-induced neutralizing Wild-type strain and Alpha, Beta, and Delta variants of severe acute respiratory syndrome coronavirus 2*

Neutralization test detection method Slope coefficient (95% CI) Half-time coefficient, d (95% CI)
Surrogate virus neutralization test ELISA
–0.645 (–0.751 to –0.538)
83.42 (76.55–90.29)
Microneutralization assay
Wild-type 0.008 (–0.141 to 0.159) 47.17 (37.48–56.86)
Alpha –0.187 (–0.302 to –0.072) 38.57 (31.16–45.99)
Beta –0.063 (–0.121 to –0.006) 6.88 (3.20–10.57)
Delta –0.125 (–0.211 to –0.040) 12.27 (6.78–17.77)

*CoronaVac vaccine by Sinovac Biotech (

Main Article

Page created: September 16, 2021
Page updated: November 21, 2021
Page reviewed: November 21, 2021
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