What is the time of seroconversion and duration of IgM and IgG responses against SARS-CoV-2?
From previous SARS studies, it is known that the median seroconversion time for detectable IgG was 17 days after infection.31Detectable levels of SARS-specific IgG and neutralizing antibodies persisted for up to 720 days. This suggests that there is antibody-mediated protection from SARS-CoV recurrent infection for up to 2 years.32 There are inconsistent reports on the humoral response to SARS-CoV-2. One study with 285 COVID-19 patients reported that SARS-CoV-2 virus-specific IgG and IgM peaked 17–19 days and 20–22 days after symptom onset, respectively.33On the other hand, another study of 26 hospitalized COVID-19 patients showed that seroconversion could take up to 50 days.34These discrepancies may be related to the time of SARS-CoV-2 diagnosis or the clinical characteristics of each cohort and warrant additional studies.