Quantifying how single dose Ad26.COV2.S vaccine efficacy depends on Spike sequence features.

Area of Science:

• Virology
• Immunology
• Vaccinology

Background:

• The Ad26.COV2.S vaccine was evaluated in the ENSEMBLE phase 3 trial.
• COVID-19 remains a global health concern, necessitating ongoing vaccine efficacy assessment.

Purpose of the Study:

• To analyze the impact of SARS-CoV-2 genetic variations on Ad26.COV2.S vaccine efficacy.
• To investigate vaccine effectiveness against different viral lineages, including Lambda.

Main Methods:

• Analysis of SARS-CoV-2 Spike gene sequences from vaccine and placebo recipients in the ENSEMBLE trial.
• Assessment of vaccine efficacy in relation to viral genetic distance, specific amino acid changes, and neutralization escape scores.

Main Results:

• Vaccine efficacy was significantly lower against the Lambda variant compared to reference strains.
• Efficacy decreased with increasing physicochemical-weighted Hamming distance between viral sequences and the vaccine strain.
• Neutralization resistance and antibody-epitope escape scores correlated with reduced vaccine effectiveness.

Conclusions:

• SARS-CoV-2 genetic diversity, particularly concerning the Spike protein, impacts Ad26.COV2.S vaccine efficacy.
• Viral variants with significant genetic divergence may exhibit reduced susceptibility to vaccine-induced immunity.
• Further research is needed to understand and address vaccine effectiveness against emerging viral strains.