IGHG3 and COVID-19: Furthermore, a recent prospective cohort study of individuals with COVID-19 found that IgM and IgG3 levels during primary infection and after 6 months were lower among persons with PASC compared to those without (Cervia et al., 2022), while another study did not find any difference in serial antibody levels between those who did and those who did not develop post-COVID-19 symptoms (Pereira et al., 2021).