protein subunit COVID-19 vaccine

A protein subunit COVID-19 vaccine is a type of vaccine that utilizes purified fragments of the SARS-CoV-2 virus, most commonly the spike protein or its receptor-binding domain (RBD), to elicit a protective immune response. Unlike mRNA or viral vector vaccines, protein subunit vaccines do not introduce genetic material into the host cells; instead, they deliver the viral antigen directly. These vaccines are typically formulated with an adjuvant to enhance immunogenicity. Several protein subunit vaccines have been developed and authorized globally, including Novavax's Nuvaxovid (NVX-CoV2373) and Anhui Zhifei Longcom's ZF2001. In clinical research, such as the ChiCTR2200057758 trial, these vaccines are evaluated for safety and immunogenicity, particularly as heterologous booster doses in populations previously immunized with inactivated vaccines.