New COVID-19 sa-mRNA Results from CSL and Arcturus Therapeutics Demonstrate Longer Duration of Immunity Compared to Conventional COVID-19 mRNA Vaccine Booster - Seite 2

Three months post-booster GMTs were 5928 (95% CI 5414–6491, n = 369) and 2899 (2648–3175, n = 356), with a higher GMT ratio of 2·04 (1·80–2·32). Day 91 titers were equal to or greater than Day 29 titers in 205 of 369 (55·6% [95% CI 50·3–60·7]) ARCT-154 recipients, but in only 108 of 356 (30·3% [25·6–35·4]) Comirnaty recipients. Due to different rates of antibody waning, by Day 181 GMTs were 4119 (95% CI 3723–4557, n = 332) and 1861 (1667–2078, n= 313) in ARCT-154 and Comirnaty groups, respectively, maintaining a GMT ratio of 2·21 (1·91–2·57) between vaccine groups. GMTs against Wuhan-Hu-1 remained numerically higher 180 days after ARCT-154 than those observed 28 days after the Comirnaty booster.

The same pattern of superior immunogenicity and slower decline in Omicron BA.4/5 neutralizing antibodies was observed: GMTs were comparable at baseline (GMT ratio of 0.94 (95% CI 0.71-1.26), and increased to 2125 (95% CI 1841–2453) vs. 1624 (1418–1858) at Day 29 after ARCT-154 and Comirnaty, then waned to 1892 (1646–2175) and 888 (764–1031), respectively, at Day 91. Between Days 29 and 91 titers were stable or increased in 128 of 369 (34·7% [95% CI 29·8–39·8]) ARCT-154 recipients, compared with 36 of 356 (10.1% [7·2–13·7]) in the Comirnaty group. The difference in neutralizing activity against Omicron BA.4/5 was maintained to Day 181 when GMTs were 1119 (95% CI 960–1305) and 495 (413–595), with a GMT ratio of 2·26 (1·78–2·86) in favor of ARCT-154.

About sa-MRNA

mRNA vaccines help protect against infectious diseases by providing a blueprint for cells in the body to make a protein to help our immune systems recognize and fight the disease. Different from standard mRNA vaccines, self-amplifying mRNA vaccines instruct the body to make more mRNA and protein to boost the immune response.

About CSL

CSL (ASX:CSL; USOTC:CSLLY) is a global biotechnology company with a dynamic portfolio of lifesaving medicines, including those that treat hemophilia and immune deficiencies, vaccines to prevent influenza, and therapies in iron deficiency and nephrology. Since our start in 1916, we have been driven by our promise to save lives using the latest technologies. Today, CSL – including our three businesses: CSL Behring, CSL Seqirus and CSL Vifor – provides lifesaving products to patients in more than 100 countries and employs 32,000 people. Our unique combination of commercial strength, R&D focus and operational excellence enables us to identify, develop and deliver innovations so our patients can live life to the fullest. For inspiring stories about the promise of biotechnology, visit CSLBehring.com/Vita and follow us on Twitter.com/CSL. For more information about CSL, visit www.CSL.com.