目前市面上的疫苗：

1. mRNA 疫苗: 關於背後的原理這裡多說，網路一堆資源
2. DNA 疫苗:
3. 減毒疫苗
4. 次單位疫苗 (subunit)

次單位疫苗在有佐劑幫助下，也有機會藉由樹突細胞Cross-presentation將抗原以MHC-I呈現給T-cell，不過畢竟效率比較差，mRNA及腺病毒載體疫苗能模擬真實病毒感染，在宿主細胞內製造S蛋白時就能順便以MHC-I呈現了~

S-specific T-cell activation

ELISA確認

T-cell activation marker

Phase 2受試者的PBMC

高端才是用CpG喔，Novavax是用他們自家佐劑Matrix-M(基於Saponin。高端是因為Subunit形式本身就比較難引起T-cell response

protein product issue is hard to validate structure correctly.

Mix-and-match COVID vaccines trigger potent immune response

A Thermostable mRNA Vaccine against COVID-19

T cells recognize recent SARS-CoV-2 variants

Development of CpG-adjuvanted stable prefusion SARS-CoV-2 spike antigen as a subunit vaccine against COVID-19

FDA Authorizes Pfizer-BioNTech COVID-19 Vaccine for Emergency Use in Adolescents

FDA briefing materials point to immune bridging studies for pediatric COVID-19 vaccines

Phase 1–2 Trial of a SARS-CoV-2 Recombinant Spike Protein Nanoparticle Vaccine

Novavax Announces Positive Phase 1 Data for its COVID-19 Vaccine Candidate

Evaluating the neutralizing ability of a CpG-adjuvanted S-2P subunit vaccine against SARS-CoV-2 Variants of Concern