The race to find a COVID-19 vaccine produced different vaccines which, after finishing clinical trials, were approved for use in several countries.
The COVID-19 vaccine was produced at an incredible speed, breaking record times for vaccine developments. The results of the trials were much better than expected, judging by their efficacy levels: the Pfizer-BioNTech vaccine recorded 95 percent efficacy in reducing infection, the Moderna vaccine 94 percent, and Oxford-AstraZeneca 90 percent.
Though efficacy and effectiveness are often used interchangeably to talk about how successful a vaccine is, efficacy refers strictly to how well a vaccine does during clinical trials, while effectiveness indicates the ability of the vaccine to prevent the disease in the real world.
Efficacy and effectiveness of a vaccine may differ, as a vaccine may perform differently in a larger setting, given to a broader population including people suffering from other health conditions.