Markers of immune activation and inflammation in individuals with post-acute sequelae of SARS-CoV-2 infection

BACKGROUND: The biological processes associated with post-acute sequelae of SARS-CoV-2 infection (PASC) are unknown. METHODS: We measured soluble markers of inflammation in a SARS-CoV-2 recovery cohort at early (<90 days) and late (>90 days) timepoints. We defined PASC as the presence of one or more COVID-19-attributed symptoms beyond 90 days. We compared fold-changes in marker values between those with and without PASC using mixed effects models with terms for PASC and early and late recovery time periods. RESULTS: During early recovery, those who went on to develop PASC generally had higher levels of cytokine biomarkers including TNF-alpha (1.14-fold higher mean ratio, 95%CI 1.01-1.28, p=0.028) and IP-10 (1.28-fold higher mean ratio, 95%CI 1.01-1.62, p=0.038). Among those with PASC, there was a trend toward higher IL-6 levels during early recovery (1.28-fold higher mean ratio, 95%CI 0.98-1.70, p=0.07) which became more pronounced in late recovery (1.44-fold higher mean ratio, 95%CI: 1.11-1.86, p<0.001). These differences were more pronounced among those with a greater number of PASC symptoms. CONCLUSIONS: Persistent immune activation may be associated with ongoing symptoms following COVID-19. Further characterization of these processes might identify therapeutic targets for those experiencing PASC.