Reports: Pfizer and Moderna allege ‘declining vaccine efficacy’ to push booster shot The first patient enrolled in Pfizer’s COVID-19 coronavirus vaccine clinical trial at the University of Maryland School of Medicine in Baltimore receives an injection. (University of Maryland School of Medicine via AP) OAN Newsroom UPDATED 3:23 PM PT – Monday, July 12, 2021 COVID-19 vaccine manufacturers have stirred up speculation of declining vaccine efficiency in efforts to promote booster shots. In a series of statements, Pfizer and Moderna claimed real-world data has shown their vaccine efficiency fell short of 90 percent, especially in older patients. As a result, the two companies suggested fully vaccinated individuals would need a third shot or a “booster.” However, both the Centers for Disease Control and Prevention and U.S. Federal Drug Administration announced a booster shot was not needed at this time.