The term "bivalent" refers to something that has two values or components. In biology, it often describes a pair of homologous chromosomes that come together during the process of meiosis, where they exchange genetic material. This pairing is crucial for genetic diversity in organisms. In the context of vaccines, "bivalent" indicates that a vaccine targets two different strains of a virus. For example, a bivalent COVID-19 vaccine is designed to protect against two variants of the SARS-CoV-2 virus. This approach enhances immunity and helps in controlling the spread of infectious diseases.