False-positive SARS-CoV-2 serology in 3 children with Kawasaki disease

Kelvin KW TO, Gilbert T. CHUA, Ka Li KWOK, Joshua SC WONG, Dennis Chi Yu AU, Yuen Yu LAM, Wilfred HS WONG, Marco HK HO, Godfrey CF CHAN, Celine SL CHUI, Xue LI, Keith TS TUNG, Rosa Sze Man WONG, Winnie WY TSO, Ian CK WONG, Christina SM WONG, Carol HY FONG, Kwok Hung CHAN, Kwok Yung YUEN, Patrick IPMike YW KWAN

Research output: Contribution to journalArticlespeer-review

13 Citations (Scopus)


Background: Kawasaki disease (KD) is an acute febrile and eruptive disease with systemic vasculitis predominantly affecting young East Asian children. Recent reports showed that children with KD-like disease from KD low prevalence regions had positive SARS-CoV-2 serology despite a negative SARS-CoV-2 polymerase chain reaction (PCR) in respiratory samples. 

Objectives: To describe 3 pediatric Kawasaki Disease patients with false positive SARS-CoV-2 serology. 

Study design: We retrospectively recruited children with KD diagnosed during the COVID-19 outbreak in Hong Kong. Clinical characteristics and laboratory test results including SARS-CoV-2 PCR results were retrieved. We performed a microparticle-based immunoassay for the detection of IgG against nucleoprotein (NP) and spike protein receptor binding domain (RBD), and a microneutralization assay for the detection of neutralizing antibodies. 

Results: Three Chinese children with typical KD were identified. They had no epidemiological links with COVID-19 patients and tested negative for SARS-CoV-2 NPA PCR. They were treated with IVIG and aspirin, and were discharged without complications. Subsequently 2 of them were tested positive against anti-RBD and anti-NP antibodies and 1 was tested positive against anti- RBD antibodies. However, microneutralization assay showed that neutralizing antibodies were absent, suggesting a false-positive IgG result. 

Conclusion: Detection of neutralizing antibodies is recommended to confirm previous SARS-CoV-2 infection in IgG-positive but PCR-negative patients. Copyright © 2020 The Author(s). Published by Elsevier Inc.

Original languageEnglish
Article number115141
JournalDiagnostic Microbiology and Infectious Disease
Issue number3
Early online dateJul 2020
Publication statusPublished - Nov 2020


To, K. K. W., Chua, G. T., Kwok, K. L., Wong, J. S. C., Au, D. C. Y., Lam, Y. Y., Wong, W. H. S., Ho, M. H. K., Chan, G. C. F., Chui, C. S. L., Li, X., Tung, K. T. S., Wong, R. S., Tso, W. W. Y., Wong, I. C. K., Wong, C. S. M., Fong, C. H. Y., Chan, K. H., Yuen, K. Y., . . . Kwan, M. Y. W. (2020). False-positive SARS-CoV-2 serology in 3 children with Kawasaki disease. Diagnostic Microbiology and Infectious Disease, 98(3), Article 115141. https://doi.org/10.1016/j.diagmicrobio.2020.115141


  • Kawasaki disease
  • COVID-19
  • False positive
  • Serology
  • Chinese


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