The coronavirus disease 2019 (COVID-19) has been a challenge for the whole world since
the beginning of 2020, and COVID-19 vaccines were considered crucial for disease eradication.
Instead of producing classic vaccines, some companies pointed to develop products that mainly
function by inducing, into the host, the production of the antigenic protein of SARS-CoV-2 called
Spike, injecting an instruction based on RNA or a DNA sequence. Here, we aim to give an overview
of the safety profile and the actual known adverse effects of these products in relationship with their
mechanism of action. We discuss the use and safety of these products in at-risk people, especially
those with autoimmune diseases or with previously reported myocarditis, but also in the general
population. We debate the real necessity of administering these products with unclear long-term
effects to at-risk people with autoimmune conditions, as well as to healthy people, at the time of
omicron variants. This, considering the existence of therapeutic interventions, much more clearly
assessed at present compared to the past, and the relatively lower aggressive nature of the new
viral variants.