Multiple vaccines in the pipeline, mostly against spike (S) protein in SARS-CoV-2 that facilitates host cell entry.

Pfizer vaccine is mRNA vaccine, completely in vitro derived, uses nanoparticles to aide absorption into host cells which then produce the S protein themselves from the mRNA. AstraZeneca vaccine is chimp adenovirus vector for genetic sequence – mRNA produced once virus taken up by host cell.

Single dose IM injection.