SARS-CoV-2-specific humoral and cellular immunity assessment in Peruvian vaccinated population: a cross-sectional...

Evaluating both humoral and cellular immunity is essential for optimizing vaccination strategies and preventing post-pandemic SARS-CoV-2 outbreaks. This cross-sectional study assessed cellular immunity by measuring CXCL10 mRNA expression and humoral immunity through SARS-CoV-2-specific IgG antibodies.

Whole blood samples were collected from 40 Peruvian volunteers. CXCL10 expression was evaluated in blood samples stimulated with Spike protein peptides from the Wuhan strain and Omicron BA.5 variant using RT-qPCR. Anti-spike IgG levels were measured with a semi-quantitative ELISA.

The median age was 31 years, with 62.5% females. A heterologous vaccination scheme was reported by 73%, but only 25% received their last dose within the past 6 months, and 55% completed three doses. The BNT162b2 vaccine was included in 88% of vaccination schemes, serving as the first and second dose in 48% of cases. All participants had detectable anti-spike IgG antibodies; 90% exhibited cellular responses to Wuhan peptides and 97.5% to Omicron peptides. CXCL10 mRNA expression (2^-ΔΔCT) was significantly higher for Omicron (median: 565.97; IQR: 565,148.34) compared to Wuhan (median: 18.55; IQR: 62,898.67). Higher anti-spike IgG levels correlated with age and the number of vaccine doses. Males had significantly higher CXCL10 and anti-spike IgG levels (p < 0.05). Antibody levels were greater in those recently boosted or vaccinated with mRNA-1273 (p = 0.001, p = 0.002).

Most participants exhibited robust immunity, characterized by elevated levels of CXCL10 and anti-SARS-CoV-2 IgG antibodies. These findings highlight the importance of boosters in enhancing immunity and the need for diverse techniques for measuring immunity.