rC19

rC19 is a recombinant COVID-19 vaccine component that has been used in combination with other vaccines, such as high-dose seasonal influenza virus vaccines, to create multivalent or combination vaccines targeting both influenza and SARS-CoV-2. In these combinations (e.g., IIV-HD + rC19), the product is designed for the prevention of COVID-19 and influenza infections. The mechanism of action involves immunostimulation—eliciting an immune response against SARS-CoV-2 through presentation of recombinant viral antigens. The vaccine is typically administered via intramuscular injection and may be adjuvanted to enhance immunogenicity. Development efforts have included companies like Sanofi, with clinical trials reaching Phase I/II for both COVID-2019 infections and influenza virus infections[4][3].