Safety and Immunogenicity of SW-BIC-213, a Modified COVID-19 Lipo-Polyplex mRNA Vaccine, in Laotian Healthy Adults Aged 18 Years and Above: A Phase 1/2 Trial

We evaluated the safety and immunogenicity of SW-BIC-213, a Lipo-Polyplex (LPP)-based mRNA vaccine against SARS-CoV-2, administered as a two-dose regimen 21 days apart in healthy adults in Laos. In this phase 1/2 trial, healthy adults aged 18–60 years (phase 1) or ≥18 years (phase 2) were enrolled at Mahosot Hospital (Vientiane) and Champhone District Hospital (Savannakhet). In phase 1, 41 participants received either 25 μg or 45 μg of SW-BIC-213. In phase 2, 480 participants were randomized (2:2:1) to receive 25 μg, 45 μg, or placebo. Primary endpoints were safety (phase 1) and safety and immunogenicity (phase 2). In phase 1, all adverse reactions were grade 1–2. In phase 2, grade 3 adverse reactions were limited to transient fever. At 14 days after the second dose, seroconversion rates of pseudovirus neutralizing antibodies exceeded 99% against wild-type virus, 98% against Delta, 84% against Omicron BA.1, and 88% against BA.2. Neutralizing antibody titers were significantly higher in both vaccine groups than in the placebo group (P< 0.0001). SW-BIC-213 demonstrated a favorable safety profile and robust immunogenicity in adults aged ≥18 years.