Last Monday, the Pfizer - BioNTech vaccine received final approval from the US Food and Drug Administration (FDA). It is important to clarify that this approval does not mean that the vaccine was experimental until last Sunday. The experimental phase of this vaccine culminated with clinical trials in November 2020. During this experimental phase the company, in this case Pfizer, gathered the necessary evidence to determine that the vaccine is safe and over 90% effective in protecting against COVID-19 . Although its effectiveness has decreased somewhat with the appearance of the delta variant, the vaccine is still the best weapon to protect us from serious illness, hospitalization, or death from COVID-19.