This review takes into consideration the principal vaccines developed against 
the SARS-CoV-2 in this unprecedented period of Covid-19 pandemic. We evaluated 
the mechanism of action of each vaccine as well as the efficacy, the safety and 
the storage temperature. In addition, the problem of the dose units, the 
vaccinal strategy, the activity of alternative compounds such as the monoclonal 
antibodies and especially the issue of the virus variants were also described in 
detail. Four vaccines are currently used in Italy: Pfizer-BioNTech mRNA BNT162b2 
(Comirnaty) (USA), Moderna mRNA 1273 (USA), Astra-Zeneca ChAdOx1-S (recombinant) 
viral vector adenovirus belonging to Oxford (UK) and Pomezia (Italy), Janssen 
(two recombinant viral vector adenoviruses) belonging to Johnson & Johnson 
(USA). The efficacy of Pfizer and Moderna for preventing disease or severe 
disease results 95-87.5% and 94.5-100%, respectively. The efficacy of 
Astra-Zeneca and Janssen is about 70% and 65%, respectively; in the case of 
Janssen, it depends on the geographical area ranging from 72% to 57%. The 
problem of the administrated doses (one dose, two doses from the same vaccine or 
from different vaccines, half dose) is also discussed. The vaccination strategy 
based on the age group remains the simplest, most transparent and fair 
criterion. This strategy is also based on accelerating the administration of the 
vaccines, so that as many subjects as possible can be vaccinated quickly for 
achieving the "herd immunity". The monoclonal antibodies appeared to be a valid 
solution for the treatment of Covid-19 disease. Two antibodies (bamlanivimab and 
etesevimab) have just been approved by the FDA. They could also be used for the 
infection by virus variants which represent a big problem due to their higher 
transmissibility and virulence and to their lower response to the vaccines.