The earliest vaccines injected at tiny amount of the disease, from smallpox on. So she probably expected to feel like shit, and that's why she felt like shit.

However the covid vaccines did not have any covid in them. So there is no way she got a taste of covid shittyness.

Most traditional vaccines consist of either killed or weakened forms of a virus or bacterium. These provoke an immune response that allows the body to fight off the actual pathogen later on.

Instead of delivering a virus, RNA vaccines deliver genetic information that allows the body’s own cells to produce a viral protein which stimulate the immune system to mount a response, without posing any risk of infection.