A viral vector vaccine uses a harmless virus to deliver genetic material from a pathogen, such as a virus or bacterium, into the body. This genetic material instructs cells to produce a harmless piece of the pathogen, prompting the immune system to recognize and respond to it. This process helps the body build immunity without causing the disease. These vaccines are designed to trigger a strong immune response, preparing the body to fight off the actual pathogen if exposed in the future. Examples of viral vector vaccines include those developed for COVID-19, such as the Johnson & Johnson and AstraZeneca vaccines.