ExpreS2ion Biotech Holding AB's affiliate ExpreS2ion Biotechnologies ApS ("ExpreS2ion") announced that follow-up results from Bavarian Nordic's Phase II clinical trial for the ABNCoV2 capsid virus-like particle (cVLP) based COVID-19 booster vaccine show that antibody titers remained high at levels associated with greater than 90% efficacy six months after vaccination for both the Wuhan and the Omicron variant. Previously reported results from the trial showed that vaccination with 100ug ABNCoV2 in 103 seropositive subjects was able to demonstrate a strong boosting effect, increasing the existing levels of SARS-CoV-2 neutralizing antibodies against the Wuhan variant and variants of concern (Alpha, Beta, Delta and Omicron) to levels reported to be highly efficacious (>90%) against SARS-CoV-2. For the follow-up analysis, 41 subjects were followed for six months post vaccination. From this group, two subjects with confirmed COVID-19 disease were excluded from the immune analysis.

Six months post vaccination, neutralization titers were six times higher than pre-boost titers against Wuhan and nearly 10 times higher than the pre-boost titers for Omicron BA.1. This represented less than a 50% decline in the peak neutralizing titers after six months and compared to the data published for mRNA vaccines, the antibody decay appears less sharp, indicating a potentially longer duration of protection across variants of concern.