Arcturus Reports Durability Data Against Omicron Variants, Including BA.5, at Six-Month Timepoint Following Booster with ARCT-154 COVID-19 Vaccine
New clinical data demonstrate high and sustained geometric mean fold rises (GMFR) in neutralizing antibodies against all evaluated Omicron variants
Six months after booster dose of ARCT-154:
BA.1: GMFR = 22 to 52; Titer = 674 to 1524
BA.2: GMFR = 25 to 55; Titer = 777 to 1713
BA.5: GMFR = 9 to 24; Titer = 295 to 730
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Exploratory pseudovirus microneutralization (MNT) assay results (left: BA.1, middle: BA.2, right: BA.5), showing geometric mean fold rise (GMFR) levels of neutralizing antibody responses over Day 1 (baseline levels prior to boosting with 5 mcg ARCT-154) calculated with virus neutralization concentrations (with 95% C.I.) obtained for n=12 participants at days 29 and 91. In Figure A, three participants were removed from the day 181 analysis (n=9, day 181): two participants received off-study vaccines during the period between day 91 and day 181, and one participant has a confirmed COVID-19 diagnosis with mild symptoms during this same period. In Figure B, three additional participants with suspected asymptomatic seroconversion were removed from the day 181 analysis (n=6, day 181). Neutralizing antibody responses against Omicron variants BA.1, BA.2, and BA.5 were measured at the
“Our next generation low-dose self-amplifying (STARR™) mRNA technology continues to differentiate itself from conventional mRNA vaccine technology as a highly and broadly immunogenic endemic vaccine platform with durable responses against the most challenging variants including Omicron BA.5 for at least 6 months,” said
Data shown above illustrate the ongoing antibody responses to single, low (5 microgram) booster doses of ARCT-154 in healthy adults (n=12) previously vaccinated with Comirnaty®. Samples taken at one, three, and six months after vaccination are shown.
After one month (day 29) and three months (day 91), neutralizing antibody responses to Omicron BA.5 were 33- and 20-fold elevated over pre-boost responses, respectively. After six months (day 181), neutralizing antibody responses to Omicron BA.1, BA.2, BA.5 ranged from 22- to 52-fold, 25- to 55-fold, and 9 to 24-fold elevated over pre-boost responses, respectively.
These data show sustained neutralizing responses to antigenically distinct variants of concern, including Omicron BA.5, for at least six months after vaccination.
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