<p>Syncytia formation occurs when viruses fuse cells together, creating multinucleated cells. By spreading through fusion, the virus avoids the extracellular environment, protecting it from antibodies that can neutralize the virus. To investigate the effect of this protection, we used a mathematical model to simulate viral infections that spread via both cell-free transmission and syncytia formation and included the effect of antibodies. We compared infections with high, low, and no syncytia fusion, finding that even a low rate of syncytia formation affects infection dynamics and can hinder antibody effectiveness. Specifically, we find that the presence of syncytia increases the viral load, delays the time of peak, and increases the number of cells infected by the virus as compared to infections without syncytia formation. This mathematical model sheds light on how syncytia formation shields viruses from antibodies, aiding in spread of the virus in spite of a robust immune response.</p>