IL6 and infection: While rheumatoid factor, antinuclear antibodies, and antiphospholipid antibodies showed no correlation with post-acute COVID-19 sequelae, analysis of blood samples from participants with ongoing post-COVID19 sequelae, revealed at 6 and 8 months after infection, increased levels of the pro-inflammatory cytokines TNF-α, IL-1β and IL-6 in close correlation with symptoms of the post-acute COVID-19 syndrome (220).