A group of Chulalongkorn Univ. reported the IgG response of patients with the new coronavirus (COVID-19) in Thailand as follows:
The study is based on data from 384 patients analyzed between March 10 and May 31, 2020.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0240502
IgG in serum comes up two weeks after infection.
In patients with mild infection, IgG was not detected in 20% of patients 2 weeks after infection.
The expression level of IgG increases as mild, moderate, severe and symptoms become heavier.
Men have higher expression of IgG than women.
The reported tendency on IgG correlates with other reports published.