Asymptomatic COVID-19 re-infection in a Japanese male by elevated half-maximal inhibitory concentration (IC50) of neutralizing antibodies.

Abstract

INTRODUCTION:

"Re-infection" with COVID-19 is a growing concern; re-infection cases have reported worldwide. However, the clinical characteristics of SARS-CoV-2 re-infection, including the levels and role of anti-SARS-CoV-2 Spike protein IgG antibodies and the half-maximal concentration (IC50) of neutralizing antibodies remain unknown.

METHODS:

Both the epidemiological and clinical information has been collected during two episodes of COVID-19 in a patient. Laboratory results, including RT-PCR, Ct values, anti-SARS-CoV-2 Spike protein IgG antibodies, and the IC50 of neutralizing antibodies levels were analyzed on the patient.

RESULTS:

The patient was a 58-year-old man who developed moderate COVID-19 pneumonia with oxygen demand (cannula 2 L/min) in the first episode. By day 30, he recuperated and was discharged after testing negative for SARS-CoV-2. After two and a half months, his three family members showed COVID-19 symptoms and tested positive for SARS-CoV-2. He tested positive for SARS-CoV-2 once again and was asymptomatic (the second episode). The IC50 of neutralizing antibodies against SARS-CoV-2 greatly increased from 50.0 μg/mL (after the first episode) to 14.8 μg/mL (after the second episode), and remained strongly reactive (20.1 μl/mL) after 47 days of the second episode.

CONCLUSIONS:

Epidemiological, clinical, and serological analyses confirmed that the patient had re-infection instead of persistent viral shedding from first infection. Our results suggest that SARS-CoV-2 re-infection may manifest as asymptomatic with increased neutralizing antibody levels. Further studies such as the virus characteristics, immunology, and epidemiology on SARS-CoV-2 re-infection are needed.

• Authors: Makoto Inada, Masahiro Ishikane, Mari Terada, Akihiro Matsunaga, Kenji Maeda, Kiyoto Tsuchiya, Kenji Miura, Yu Sairenji, Noriko Kinoshita, Mugen Ujiie, Satoshi Kutsuna, Yukihito Ishizaka, Hiroaki Mitsuya, Norio Ohmagari
• Journal: Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy (J Infect Chemother) Vol. 27 Issue 7 Pg. 1063-1067 (Jul 2021) ISSN: 1437-7780 [Electronic] Netherlands
• PMID: 33962861 (Publication Type: Case Reports, Journal Article)
• Copyright: Copyright © 2021 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Chemical References

• Antibodies, Neutralizing
• Antibodies, Viral

Topics

• Antibodies, Neutralizing
• Antibodies, Viral
• COVID-19
• Humans
• Japan
• Male
• Middle Aged
• Reinfection
• SARS-CoV-2