New COVID-19 mRNA vaccine is safe and highly immunogenic as a heterologous booster: Study

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in more than 600 million confirmed cases and 6.5 million deaths worldwide. mRNA-based vaccines have emerged as a leading platform for COVID-19 protection and are extensively investigated in basic and clinical trials. SYS6006 (CSPC Pharmaceutical Group) is a newly investigational COVID-19 mRNA vaccine encoding a full-length S protein sequence of the prototype SARS-CoV-2 strain and incorporating the key mutations of main epidemic variants. In March 2023, it has been authorized for emergent use in China by the national medicinal product agency (NMPA) of China. Yet, the data from clinical trials have not been published before. Moreover, the third dose of inactivated vaccine of COVID-19 has been proposed as the initial boosting regimen, and the second heterologous booster (the fourth dose of the vaccine) is worth investigating. By enrolling eligible healthy subjects and convalescent COVID-19 patients, researchers from Shanghai Xuhui...