Antibody Responses in COVID-19 Patients Could Guide Vaccine Design

A comprehensive analysis of antibody responses in patients with coronavirus disease 2019 (COVID-19) could inform the development of an effective vaccine, according to a study published Sept. 10 in the open access journal. PLOS Pathogens by Chao Wu and Rui Huang of Nanjing University School of Medicine, and colleagues. The results show that the neutralizing activity of the recovered patients’ antibodies is generally not strong and decreases dramatically within a month after discharge from hospital.

The world faces an unprecedented challenge with communities and economies affected by the growing COVID-19 pandemic. Currently, there is no vaccine or effective drugs approved to treat or prevent the disease. A better understanding of antibody responses to SARS-CoV-2, the virus that causes COVID-19, will provide critical information for developing effective treatments and a preventive vaccine. In the new study, researchers continuously monitored SARS-CoV-2 specific antibody responses in 19 non-severe and seven severe COVID-19 patients for seven weeks from the onset of the disease.

The majority of patients generated antibody responses against SARS-CoV-2, including the viral nucleoprotein and three parts of the spike protein: the receptor-binding domain, the S1 protein, and the ectodomain. Although 80.7% of recovered COVID-19 patients had varying levels of neutralizing activity for antibodies to SARS-CoV-2, only a small fraction of patients elicited a potent level of neutralizing activity. This result highlights the importance of carefully selecting blood samples from patients recovered by antibody neutralization assays prior to transfusion to other COVID-19 patients. Three to four weeks after hospital discharge, the antibody neutralizing activity of recovered patients was significantly reduced, suggesting that recovered COVID-19 patients might be susceptible to re-infection by SARS-CoV-2. Additionally, patients with severe COVID-19 had a large number of non-neutralizing antibodies, which may contribute to the increase in antibody-dependent infection. According to the authors, the study provides important information for serological testing, antibody-based intervention, and vaccine design.