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Title: Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine breakthrough infections: a multicentre cohort study
Authors: Chia, Po Ying
Ong, Sean Wei Xiang
Chiew, Calvin J.
Ang, Li Wei
Chavatte, Jean-Marc
Mak, Tze-Minn
Cui, Lin
Kalimuddin, Shirin
Chia, Wan Ni
Tan, Chee Wah
Chai, Louis Yi Ann
Tan, Seow Yen
Zheng, Shuwei
Lin, Raymond Tzer Pin
Wang, Linfa
Leo, Yee Sin
Lee, Vernon J.
Lye, David C.
Young, Barnaby Edward
Keywords: Science::Medicine
Issue Date: 2022
Source: Chia, P. Y., Ong, S. W. X., Chiew, C. J., Ang, L. W., Chavatte, J., Mak, T., Cui, L., Kalimuddin, S., Chia, W. N., Tan, C. W., Chai, L. Y. A., Tan, S. Y., Zheng, S., Lin, R. T. P., Wang, L., Leo, Y. S., Lee, V. J., Lye, D. C. & Young, B. E. (2022). Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine breakthrough infections: a multicentre cohort study. Clinical Microbiology and Infection, 28(4), 612.e1-612.e7.
Project: COVID19RF-001
Journal: Clinical Microbiology and Infection
Abstract: Objectives: Highly effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) have been developed but variants of concerns are worrisome, especially B.1.617.2 (Delta) which has rapidly spread across the world. We aim to study if vaccination alters virological and serological kinetics in breakthrough infections. Methods: We conducted a multicentre retrospective cohort study of patients in Singapore who had received a licensed mRNA vaccine and been admitted to hospital with B.1.617.2 SARS-CoV-2 infection. We compared clinical features, virological and serological kinetics (anti-nucleocapsid, anti-spike and surrogate virus neutralization titres) between fully vaccinated and unvaccinated individuals. Results: Out of 218 individuals with B.1.617.2 infection, 84 received an mRNA vaccine of which 71 were fully vaccinated, 130 were unvaccinated and four received a non-mRNA vaccine. Despite significantly older age in the vaccine breakthrough group, only 2.8% (2/71) developed severe COVID-19 requiring oxygen supplementation compared with 53.1% (69/130) in the unvaccinated group (p < 0.001). Odds of severe COVID-19 following vaccination were significantly lower (adjusted odds ratio 0.07 95% CI 0.015 e0.335, p 0.001). PCR cycle threshold values were similar between vaccinated and unvaccinated groups at diagnosis, but viral loads decreased faster in vaccinated individuals. Early, robust boosting of anti-spike protein antibodies was observed in vaccinated patients; however, these titres were significantly lower against B.1.617.2 than the wildtype vaccine strain. Discussion: The mRNA vaccines are highly effective at preventing symptomatic and severe COVID-19 associated with B.1.617.2 infection. Vaccination is associated with faster decline in viral RNA load and a robust serological response. Vaccination remains a key strategy for control of the COVID-19 pandemic.
ISSN: 1198-743X
DOI: 10.1016/j.cmi.2021.11.010
Schools: Lee Kong Chian School of Medicine (LKCMedicine) 
Organisations: National Centre for Infectious Diseases
Tan Tock Seng Hospital
Yong Loo Lin School of Medicine, NUS
Rights: © 2021 The Author(s). Published by Elsevier Ltd on behalf of European Society of Clinical Microbiology and Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http://
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:LKCMedicine Journal Articles

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