WestVac Biopharma and its subsidiary company WestVac Biopharma (Guangzhou) leveraged the rapid response of the insect cell expression platform on constructing the vector for Coviccine® Trivalent XBB.1.5-Recombinant COVID-19 Trivalent (XBB.1.5+BA.5+Delta) Protein Vaccine (Sf9 Cell), which is of high purity and high quality for human use. The subunit vaccine antigen is precisely designed based on the structure of the targeting S-RBD and HR proteins of the COVID-19 subvariants XBB.1.5 and BA.5 and self-assembled into stable trimeric protein particles with squalene-based oil-in-water emulsion adjuvant added after purification and mixing. This novel adjuvant significantly raises the titer of neutralizing antibodies, which enables the trimeric protein vaccine to induce a higher level T-cell immune response. Studies have shown that Coviccine® Trivalent XBB.1.5 induced a high titer of neutralizing antibodies against multiple subvariants, including Omicron subvariants XBB.1.5, XBB1.16, XBB1.9.1, XBB.2.3, BA.5, BF.7, BQ.1, BA.2.75. 14 days after injection of this product, the protective efficacy against XBB.1, XBB.1.5, XBB1.9 is 93.28% with an excellent safety profile, demonstrating that it is a broad-spectrum COVID-19 vaccine against multiple prevalent subvariants locally and internationally.

The XBB.1.5 variant had gradually become the major circulating variant in various parts of the world by the beginning of 2023. With the professional guidance and support from the State Council's Joint Prevention and Control Mechanism's vaccine R&D team, the scientific team of WestVac Biopharma/West China Medical Center, Sichuan University overcame all hurdles and successfully developed a vaccine covering XBB family of variants.

Early May, China CDC expert noticed that the transmission and immune escape capability of XBB variants is much stronger than that of the early circulating Omicron variants. The XBB.1 descendent lineages currently predominate SARS-CoV-2 circulation globally. As of the end of May, XBB family of variants accounted for 98.1% of all variants in the United States. In China, newly detected XBB variants have increased gradually and now exceed 90%.

The WHO Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) advised on May 18 that new formulations of COVID-19 vaccines should aim to induce antibody responses that neutralize XBB descendent lineages. The rate of "second infection" is rising. Experts urge prompt prevention, immunization against COVID-19, particularly for people with high-risk infection, the elderly, people with underlying diseases and those who are immunocompromised to get a vaccine covering SARS-CoV-2 variants.

WestVac Biopharma uses the international advanced insect cell recombinant protein vaccine platform to develop Coviccine® Trivalent XBB.1.5 which has been approved for EUA in China. WestVac's COVID-19 vaccine offers a unique option for COVID-19 prevention, is crucial for the prevention of the current XBB descendent lineages and contributes significantly to the ongoing management of the COVID-19 epidemic.