The Moderna and Pfizer-BioNTech COVID-19 vaccines are not live. These vaccines are made with genetic particles called messenger RNA (mRNA), which provide instructions for your cells to make harmless microscopic material called spike protein. The presence of the spike protein prompts your immune system to develop antibodies against COVID-19 infections.
You may also be interested to know that these vaccines do not contain egg, which is an ingredient in some vaccines. They are also free of fetal cells, viral cells and preservatives.
The Johnson & Johnson vaccine uses a virus. However, it is not a coronavirus. Instead, a version of Adenovirus 26, which does not replicate or cause illness, delivers the mRNA, instructing your cells to make the spike proteins. Moreover, just like other COVID-19 vaccines, immune-response prompting antibodies are triggered by the spike proteins' presence.