IGHE and myalgic encephalomeyelitis/chronic fatigue syndrome: To explore the relationship of HERV-W ENV protein expression with patient immune response to SARS-CoV2 infection, we measured the levels of circulating anti-SARS-CoV-2 immunoglobulins (IgG, IgM, IgA and IgE) in acute and post-COVID-19 condition cases with respect to pre-pandemic (ppHBD + CFS) and pandemic (pHBD) control groups (also after vaccination campaign started) by Simple Western technology (Figure 2).