"mRNA vaccines use mRNA created in a laboratory to teach our cells how to make a protein—or even just a piece of a protein—that triggers an immune response inside our bodies. That immune response, which produces antibodies"
https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html
"The COVID-19 vaccines are all based on supplying genetic code to produce the spike protein that is the main constituent of the SARS-CoV-2 protein cage that encloses its RNA contents."
https://www.lifesitenews.com/opinion/widespread-covid-vaccination-may-lead-to-a-spike-in-crippling-diseases-analysis/
"Most existing vaccines are prepared from an attenuated version of the pathogen or from inactivated disease-causing organisms or a suitable part of it e.g. a toxin. However, often the antigen to which the immune system responds is a relatively small number of amino acids or peptide.
A possible alternative approach to immunization would therefore be to identify the peptide sequences that trigger a protective immune response and to use completely synthetic versions of these as the vaccine substance."
https://www.who.int/teams/health-product-policy-and-standards/standards-and-specifications/vaccine-standardization/synthetic-peptide-vaccines
"the vaccine’s spike protein is “a pathogenic protein,” “a toxin”"
https://www.factcheck.org/2021/07/scicheck-covid-19-vaccine-generated-spike-protein-is-safe-contrary-to-viral-claims/
"four spike proteins (RBD, S1, S2 and a stabilized spike trimer (ST)) representing commonly used antigens"
https://pubmed.ncbi.nlm.nih.gov/34197839/
"The spike is a major focus of neutralizing antibodies and therefore of vaccine development efforts. The S1 subunit makes contact with the receptor via its receptor-binding domain (RBD)."
"The spike protein, particularly the RBD, is therefore the main antigenic target for vaccine formulation."
https://www.news-medical.net/news/20210222/An-overview-of-spike-protein-antigen-COVID-19-vaccine-candidates.aspx
"To design clinically effective peptide vaccines in the future, different issues have to be addressed and optimized comprising antigen target selection as well as choice of optimal adjuvants and vaccination schedules."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7950068/
"Spike peptides to the immune system."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8402319/
Peptide Vaccine: Progress and Challenges
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4494216/
"The mRNA sequence more or less serves as a sort of source code for the vaccine."
https://gizmodo.com/stanford-scientists-post-entire-mrna-sequence-for-moder-1846576268
"The mRNA vaccines contain only the code for the SARS-CoV-2 envelope spike protein, whereas the DNA-based vaccines both contain an adenovirus viral vector that has been augmented with DNA that codes for the SARS-CoV-2 spike protein."
https://www.lifesitenews.com/opinion/widespread-covid-vaccination-may-lead-to-a-spike-in-crippling-diseases-analysis/
"Subunit vaccines utilising only part of the whole pathogen are more controllable and can be produced without the use of the pathogen itself (e.g. recombinant proteins). They are a very attractive alternative to the whole pathogen approach and have become extensively popular in the modern era"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5529997/