COVID-19
In November 2020, two companies, Pfizer and Moderna both said their vaccines had completed some testing.  Both were over 90% effective.  Both companies asked the United States Food and Drug Administration for permission to start giving the vaccine to people.  Both the Pfizer and Moderna vaccines are messenger RNA vaccines they teach the body to recognize the virus.  They say mRNA vaccines take less time to develop and make than protein or whole-virus vaccines.