"All vaccines introduce into the body a harmless piece of a particular bacteria or virus, triggering an immune response. Most vaccines contain a weakened or dead bacteria or virus. However, scientists have developed a new type of vaccine that uses a molecule called messenger RNA (mRNA) rather than part of an actual bacteria or virus. Messenger RNA is a type of RNA that is necessary for protein production. Once cells finish making a protein, they quickly break down the mRNA. mRNA from vaccines does not enter the nucleus and does not alter DNA.
mRNA vaccines work by introducing a piece of mRNA that corresponds to a viral protein, usually a small piece of a protein found on the virus’s outer membrane"
https://medlineplus.gov/genetics/understanding/therapy/mrnavaccines/
"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 spike protein in SARS-CoV-2 (SARS-2-S) interacts with the human ACE2 receptor to gain entry into a cell to initiate infection. Both Pfizer/BioNTech’s BNT162b2 and Moderna’s mRNA-1273 vaccine candidates are based on stabilized mRNA encoding prefusion SARS-2-S that can be produced after the mRNA is delivered into the human cell and translated."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7829931/
Development of new vaccine target against SARS-CoV2 using envelope (E) protein: An evolutionary, molecular modeling and docking based study
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7833863/
Nucleocapsid as a next-generation COVID-19 vaccine candidate
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9250828/
"One of the major vaccine strategies is the use of M protein"
https://pubmed.ncbi.nlm.nih.gov/31843270/
Coronavirus fusion peptide could be important target for vaccine development
https://www.news-medical.net/news/20230904/Coronavirus-fusion-peptide-could-be-important-target-for-vaccine-development.aspx
Development of multi-epitope peptide-based vaccines against SARS-CoV-2
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7527307/