Contralateral versus ipsilateral vaccine boosting for COVID-19: considering the broader scientific landscape

In the relentless battle against the COVID-19 pandemic, the deployment of mRNA vaccines has stood out as a beacon of hope. The successes of Pfizer-BioNTech NT162b2 and Moderna mRNA-1273 vaccines have been remarkable, marking a revolutionary advancement in the field of vaccinology. Despite their rapid development and impressive efficacy, challenges have emerged, particularly concerning the waning immune response over time and the evolving landscape of SARS-CoV-2 variants. The study published in this issue of JCI by Fazli et al. introduces an approach to potentially enhancing the immune responses generated by COVID-19 mRNA vaccines. The study meticulously examines the outcomes of nearly 1,000 participants who received one or two booster doses with the Pfizer-BioNTech NT162b2 vaccine either ipsilaterally or contralaterally in relation to the initial vaccine dose. Intriguingly, those who received the booster contralaterally exhibited a heightened antibody response that was particularly noteworthy in the later time points after boost.