Advances in Infectious Diseases & Therapy

Open Access


Clinical courses of COVID-19 cases with or without SARS-CoV-2 immunoglobulin antibodies identified during quarantine at international airports in Japan

Takeuchi S, Ishii K, Koshiba H, Hara K, Wakabayashi M, Matsumoto Y, Fujihara J, Ito T, Konuma S, Aoki T, Tsubota T, Hayashi T.

Background: The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has spread around the world and been classified as a global pandemic. This study aimed to determine the factors involved in the time to disappearance of SARS-CoV-2 from nasopharyngeal swabs in patients with COVID-19.

Methods: The study participants were 22 patients diagnosed with COVID-19 whose nasopharyngeal swabs tested positive for SARS-CoV-2 by quantitative reverse transcription polymerase chain reaction (RT-qPCR) in quarantine before being admitted to our hospital. All patients underwent laboratory tests for anti-SARS-CoV-2 antibodies and chest X-ray on admission. Logistic regression analysis was conducted to investigate retrospectively the association between the number of days from nasopharyngeal to viral resolution and clinical factors.

Results: In the univariate analysis, no clinical or laboratory factors, including age, sex, highest body temperature, lowest peripheral oxygen saturation, presence of symptoms during hospitalization, laboratory results, and chest X-ray findings, were associated with negative RT-qPCR results at 5, 7, and 10 days from first detection of the virus. Although no statistically significant differences were found, the median times required until achieving two consecutive negative RT-qPCR results for SARS-CoV-2 from first detection of the virus were 5 and 10 days in cases without and with anti-SARS-CoV-2 immunoglobulin M (IgM) and/or immunoglobulin M (IgG) antibodies, respectively.

Conclusion: Although we only investigated the presence or absence of IgM and IgG antibodies to SARS-CoV-2 at the time of admission, our results suggest that humoral immunity may not be essential for the disappearance of SARS-CoV-2 in nasopharyngeal swabs.

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