Limited impact of Delta variant’s mutations in the effectiveness of neutralization conferred by natural infection or COVID-19 vaccines in a Latino population

Abstract

The SARS-CoV-2 pandemic has impacted public health systems all over the world. The Delta variant seems to possess enhanced transmissibility, but no clear evidence suggests it has increased virulence. Our data shows that pre-exposed individuals had similar neutralizing activity against the authentic COVID-19 strain and the Delta and Epsilon variants. After one vaccine dose, the neutralization capacity expands to all tested variants. Healthy vaccinated individuals showed a limited breadth of neutralization. One vaccine dose induced similar neutralizing antibodies against the Delta compared to the authentic strain. However, even after two doses, this capacity only expanded to the Epsilon variant.

Figure 1.. Neutralization capacity of sera from infected and non-infected individuals against SARS-CoV-2 Variants before and after vaccination.

The neutralization activity of sera from infected individuals (n=10) and non-infected ones (n=21) before and after vaccination was evaluated against the six variants of concern. Dotted line indicates the limit of detection of the sVNT assay, where the percentage of signal inhibition is determined (≥ 30% indicates a positive result). A Normality test (Shapiro Wilk) was performed for all data sets in order to assess the distribution of the data. The significance threshold for all analyses was set at p<0.05. A. Neutralization activity of sera from infected individuals (n=10) before vaccination. A One-Way ANOVA test with Dunnetts’s multiple comparisons test was performed between each of the variants. B. Neutralization activity of sera from healthy individuals (n=21) after receiving the 1st vaccine dose. A One-Way ANOVA test with Dunn’s Kruskal-Wallis multiple comparisons test was performed between each of the variants. C. Neutralization activity of sera from infected individuals (n=10) after receiving the first vaccine dose. A One-Way ANOVA test with Dunnett’s multiple comparisons test was performed between each of the variants. D. Neutralization activity of sera from healthy individuals (n=21) after receiving the 2nd vaccine dose. A One-Way ANOVA test with Dunn’s Kruskal-Wallis multiple comparisons test was performed between each of the variants. E. Neutralization activity of sera from infected individuals (n=10) after receiving the 2nd vaccine dose. A One-Way ANOVA test with Dunnett’s multiple comparisons test was performed between each of the variants. F. Neutralization activity of sera from vaccinated individuals, pre-exposed (n=10, depicted in circles) and healthy (n=21, depicted in squares), after receiving the 2nd dose was evaluated. A One-Way ANOVA test with Dunn’s Kruskal-Wallis multiple comparisons test was performed between each of the variants.