Moderna Inc (NASDAQ: MRNA) and Pfizer Inc. (NYSE: PFE)- BioNTech SE – ADR (NASDAQ: BNTX) for their vaccine candidates. Moderna and Pfizer-BioNTech received authorizations for their vaccine candidates in December. Unlike the messenger RNA vaccines of Moderna and Pfizer-BioNTech, J&J's vaccine candidate uses a single-dose regimen and is an experimental viral vector vaccine that uses a weakened form of adenovirus to transport genetic material to trigger immune response. J&J's vaccine candidate can remain stable for two years at -20 degrees Celsius, at least three months of which can be at te...