BNT162b vaccines protect rhesus macaques from SARS-CoV-2.
Level 5 - mechanism / opinion, no new human data
Preclinical animal and in vitro laboratory study
PubMed 33524990 · doi:10.1038/s41586-021-03275-y
What was done
Researchers characterized the structural, immunological, and protective profiles of two lipid-nanoparticle-formulated nucleoside-modified mRNA vaccine candidates against SARS-CoV-2: BNT162b1 (encoding a soluble, trimerized receptor-binding domain) and BNT162b2 (encoding a full-length, prefusion-stabilized spike protein). Immunogenicity was assessed following a single intramuscular dose in mice and prime-boost vaccination in rhesus macaques (Macaca mulatta), followed by infectious SARS-CoV-2 challenge.
What was found
Approximately 20% of BNT162b2 spike trimers adopted the two-RBD-down, one-RBD-up conformation. In mice, single-dose vaccination generated dose-dependent viral entry inhibition and strong Th1 CD4+ and IFN-gamma+ CD8+ T cell responses. In rhesus macaques, prime-boost vaccination elicited neutralizing antibody geometric mean titers 8.2- to 18.2-fold higher than a panel of human convalescent sera. Both candidates protected macaques from challenge; BNT162b2 prevented viral RNA detection in the lower respiratory tract without evidence of disease enhancement.
Why it matters
These preclinical findings provided proof-of-concept for the safety, immunogenicity, and protective efficacy of BNT162b mRNA vaccines against SARS-CoV-2, directly supporting clinical trial progression and authorization.
Limits
The abstract does not specify the exact sample sizes of mice or non-human primates evaluated. Findings are limited to animal models and require human clinical trial validation to establish safety, clinical efficacy, and durability of protection in diverse human populations.
Cited by
- supports The mRNA and Johnson & Johnson COVID-19 vaccines incorporate two proline amino acid substitutions into the SARS-CoV-2 spike protein sequence to stabilize it in a closed, prefusion conformation.