Vaccine Effectiveness – Boosters (Adults)

Key Points are meant to be a scientific, factual summary of the available information that relates solely to the Pfizer-BioNTech COVID-19 Vaccine, as supported by referenced publications within this section. Conclusions should not be drawn from the inclusion or absence of information.

• The emergence of SARS-CoV-2 variants of concern (VOC), such as Delta and Omicron highlighted waning immunity, which has been observed at > 3 months following 2 BNT162b2 vaccine doses.^1-3
• CDC has made updated recommendations for COVID-19 vaccine booster doses in individuals 5 years of age and older.^4-6
• Vaccine Effectiveness (VE) of a 3^rd and 4^th (booster) doses has been studied in Real World Evidence (RWE) studies.^{1, 2, 7-18}
• RWE on VE against several outcomes of interest (such as confirmed infection, symptomatic infection, ED visits, severe disease, and hospitalization) has varied across studies, and these cannot be compared due to differences in study design and methodology. VE% (95% CI) ranges for BNT162b2, at listed times post last vaccine dose, are summarized below for periods of Delta (B.1.617.2) and Omicron (B.1.1.529) variant predominance:

• The initial booster studies were largely conducted during the worldwide Delta and Omicron waves.^{1, 2, 7-18}
• VE has waned over time with new VOC (especially with Omicron as compared to other variants).^{2, 3, 7, 9, 17}
• BNT162b2, in the studies described in this summary, has been associated with reduction of risk against more severe outcomes, such as COVID-19 related hospitalization or death, particularly for individuals who have received booster doses.^{2, 3, 9-11, 13-16, 18}