Influence of hybrid immunity and host factors on the concentration of neutralizing antibodies against SARS-CoV-2

Abstract

Objectives: To analyze the influence of hybrid immunity and host-dependent factors on the baseline concentration of neutralizing antibodies against SARS-CoV-2.

Materials and methods: Observational study of an analytical type, cross-sectional. A sample of 169 participants, over 18 years of age, of both sexes; distributed in two groups. Group A: 84 participants with previous infection + vaccination. Group B: 85 participants without previous infection + vaccination. Baseline concentrations of total anti-RBD antibodies were measured. In all cases, a significance level α 5% was used (p= <0.05).

Results: A positive result was considered from a mean fluorescence index equal to or greater than 1.3 (MIF≥ 1.3). All participants have titles above the cut-off point. Group A: 6.8 ± 2.23 MIF, Group B: 7.39 ± 2.78 MIF. There was no statistically significant difference between them (p= 0.145). Significant differences were evidenced with males (p= 0.049), overweight (p= 0.037) and the Moderna vaccine (mRNA-1273) (p= 0.003).  A statistically significant, weak, and direct correlation was evidenced between the number of booster doses and the concentration of antibodies in group A (p= 0.013). The simple linear regression model predicts in group A that a fifth booster dose would generate antibody levels of 8.81 MIF, values much higher than the average (6.80 MIF).

Conclusions: Hybrid immunity influences the humoral response induced by vaccines, favouring increased antibody production with each booster dose received. In our population, overweight is a host-dependent factor that negatively influences the baseline concentration of antibodies in individuals with previous infections.

Keywords: Infection; SARS-CoV-2; COVID-19; Vaccines; Hybrid immunity.