CureVac N.V. announced the online publication of the extended preclinical study of the second-generation vaccine candidate, CV2CoV, jointly developed with GSK, in the journal Nature. The newly published data features a direct comparison of CV2CoV with the licensed mRNA vaccine, Comirnaty(R) (Pfizer/BioNTech). Neutralizing antibody levels measured following full vaccination of animals with either 12-g of CV2CoV or a 30-g standard dose of Comirnaty(R) were shown to be highly comparable. The data confirm how targeted optimizations of a non-chemically modified mRNA can significantly improve immune responses in a preclinical model, providing substantiated support for the unmodified mRNA technology approach. This applies not only to the development of COVID-19 vaccines but to the mRNA technology field as a whole. The study, conducted in collaboration with Dan Barouch, MD, PhD, of Beth Israel Deaconess Medical Center, investigated immune responses as well as the protective efficacy of CV2CoV and first-generation candidate, CVnCoV, against SARS-CoV-2 challenge in cynomolgus macaques. It was made available via the bioRxiv preprint server in August 2021. For additional details, please refer to the previously issued press release. About the Study: Within the study, CV2CoV and CVnCoV were tested in cynomolgus macaques immunized with a 12-g dose of the respective candidate on day 0 and day 28. For comparison with Comirnaty(R), animals were vaccinated twice, on day 0 and day 21, with 30-g of the licensed vaccine and antibody titers were measured at peak immunity at week 5. Within the comparison of CV2CoV with CVnCoV, CV2CoV consistently showed better activation of innate and adaptive immune responses, resulting in earlier response onset, higher antibody titers and stronger memory B and T cell activation. Higher antibody neutralizing capacity was observed with CV2CoV across a range of relevant variants, including the Delta variant. During challenge with the original SARS-CoV-2 virus, animals vaccinated with CV2CoV were found to be better protected than animals vaccinated with CVnCoV based on effective clearance of the virus in the lungs and nasal passages.