Pfizer-BioNTech COVID-19 Vaccine 91% Effective At Least 6 Months After 2nd Dose By Ryan Chatelain International UPDATED 9:49 AM ET Apr. 01, 2021 PUBLISHED 8:05 AM ET Apr. 01, 2021 PUBLISHED 8:05 AM EDT Apr. 01, 2021 SHARE The COVID-19 vaccine developed by Pfizer and its German partner, BioNTech, is more than 90% effective at least six months after the second dose is given, the companies announced Thursday. What You Need To Know The COVID-19 vaccine developed by Pfizer and BioNTech is more than 90% effective at least six months after the second dose is given, the companies announced Thursday Updated data from a Phase 3 clinical trial vaccine also found that the vaccine is effective against the more highly contagious variant prevalent in South Africa, the drugmakers said