Anti-SARS-CoV-2 antibody levels and kinetics of vaccine response: potential role for unresolved inflammation following recovery from SARS-CoV-2 infection

The immune response after SARS-CoV-2 vaccine administration appears to be characterized by high inter-individual variation, even in SARS-CoV-2 positive subjects, who could have experienced different post-infection, unresolved conditions. We monitored anti-SARS-CoV-2 IgG levels and kinetics along with circulating biomarkers in a cohort of 175 healthcare workers during early immunization with COVID-19 mRNA-LNP BNT162b2 vaccine, to identify the associated factors. Subjects with a previous SARS-CoV-2 infection were characterized by higher BMI and CRP levels and lower neutrophil count with respect to naive subjects. Baseline IgG levels resulted associated with CRP independently on BMI and inflammatory diseases. Among 137 subjects undergoing vaccination and monitored after the first and the second dose, three kinetic patterns were identified. The pattern showing a rapid growth was characterized by higher IgG levels at baseline and higher CRP and MCHC levels than negative subjects. Subjects previously exposed to SARS-CoV-2 showed higher levels of CRP, suggesting persistence of unresolved inflammation. These levels are the main determinant of IgG levels at baseline and characterized subjects belonging to the best performing, post-vaccine antibody kinetic pattern.

Automated summary

The immune response to the SARS-CoV-2 vaccine shows significant variation between individuals, even in those who have previously been infected with SARS-CoV-2. Individuals with prior infection have higher BMI and CRP levels, as well as lower neutrophil count compared to those without prior infection. Baseline levels of IgG are associated with CRP, independent of BMI and inflammatory diseases. Among vaccinated individuals, three patterns of antibody kinetics were observed, with the rapid growth pattern associated with higher baseline IgG levels, as well as higher CRP and MCHC levels. Those previously exposed to SARS-CoV-2 showed higher CRP levels, suggesting persistent unresolved inflammation. These CRP levels are the primary determinant of baseline IgG levels and characterize individuals with the most favorable post-vaccine antibody kinetics.