Long QX, Liu BZ, Deng HJ, Wu, et al. Antibody responses to SARS-CoV-2 in patients with COVID-19. Nat Med. 2020 Apr 29. doi: 10.1038/s41591-020-0897-1.

We report acute antibody responses to SARS-CoV-2 in 285 patients with COVID-19. Within 19 days after symptom onset, 100% of patients tested positive for antiviral immunoglobulin-G (IgG). Seroconversion for IgG and IgM occurred simultaneously or sequentially. Both IgG and IgM titers plateaued within 6 days after seroconversion. Serological testing may be helpful for the diagnosis of suspected patients with negative RT-PCR results and for the identification of asymptomatic infections.