The Trend of Neutralizing Antibody Response Against SARS-CoV-2 and the Cytokine/Chemokine Release in Patients with Differing Severities of COVID-19: All Individuals Infected with SARS-CoV-2 Obtained Neutralizing Antibody

Background: COVID-19 patients show a wide clinical spectrum ranging from mild respiratory symptoms to severe and fatal disease, and older individuals are known to be affected more severely. Neutralizing antibody for viruses is critical for their elimination, and increased cytokine/chemokine levels are thought to be related to COVID-19 severity. However, the trend of the neutralizing antibody production and cytokine/chemokine levels during the clinical course of COVID-19 patients with differing levels of severity has not been established. Methods: We serially collected 45 blood samples from 12 patients with different levels of COVID-19 severity, and investigated the trend of neutralizing antibody production using authentic SARS-CoV-2 and cytokine/chemokine release in the patients9 clinical courses. Results: All 12 individuals infected with SARS-CoV-2 had the neutralizing antibody against it, and the antibodies were induced at approx. 4-10 days after the patients9 onsets. The antibodies in the critical and severe cases showed high neutralizing activity in all clinical courses. Most cytokine/chemokine levels were clearly high in the critical patients compared to those with milder symptoms. Conclusion: Neutralizing antibodies against SARS-CoV-2 were induced at a high level in the severe COVID-19 patients, indicating that abundant virus replication occurred. Cytokines/chemokines were expressed more in the critical patients, indicating that high productions of cytokines/chemokines have roles in the disease severity. These results may indicate that plasma or neutralizing antibody therapy could be a first-line treatment for older patients to eliminate the virus, and corticosteroid therapy could be effective to suppress the cytokine storm after the viral genome9s disappearance.