Can the vaccine cause Covid

The vaccines currently in use in Italy use mRNA technology (Pfizer-Biontech and Moderna) and viral vector technology (Astrazeneca). In the first case, the mRNA vaccine induces immunity by providing human cells only with the instructions to produce a fragment of the virus, the Spike protein, which will induce the production of specific antibodies against the SARS-CoV-2 virus. Thus, no virus, either live or attenuated, is administered with these vaccines, and the spike protein alone cannot cause infection or disease. The second case is a viral vector vaccine that uses a modified version of the chimpanzee adenovirus, which is no longer able to replicate, as a DNA vector to provide instructions for synthesizing the SARS-CoV-2 spike protein in the nucleus of human cells. Once produced, the protein can stimulate a specific antibody and cell-mediated immune response. The technology is the same as that behind the first vaccine approved for Ebola in late 2019.

A possible COVID-19 disease following vaccination, can therefore be caused only by a natural infection of the virus, contracted independently from the vaccine.