How do vaccines sometimes use viral vectors to deliver protection?

In a viral vector vaccine, a modified virus such as an adenovirus carries genetic material from the disease-causing pathogen into cells. The vector cannot cause the disease it is designed to prevent, but it can produce the target protein long enough for the immune system to notice it. This strategy was used in some Ebola vaccines and in several COVID-19 vaccines. Because the vector acts like a delivery vehicle, it can be effective even when the original pathogen is difficult to grow in the lab. The immune response usually includes antibodies and T cells.