PFIZER INC

DEFINED TERMS

Unless the context requires otherwise, references to “Pfizer,” “the Company,” “we,” “us” or “our” in this Form 10-K (defined below) refer to Pfizer Inc. and its subsidiaries. For each year presented, Pfizer’s fiscal year-end for subsidiaries operating outside the U.S. is as of and for the year ended November 30 and for U.S. subsidiaries is as of and for the year ended December 31. References to “Notes” in this Form 10-K are to the Notes to the consolidated financial statements in Item 8. Financial Statements and Supplementary Data in this Form 10-K. We also have used several other terms in this Form 10-K, most of which are explained or defined below:

(a)Certain uses of Paxlovid and COVID-19 vaccines from BioNTech and Pfizer have not been approved or licensed by the FDA. Paxlovid has been authorized for emergency use by the FDA under an EUA for the treatment of mild-to-moderate COVID-19 in pediatric patients (12 years of age and older weighing at least 40 kg) who are at high risk for progression to severe COVID-19, including hospitalization or death. Emergency uses of COVID-19 vaccines from Pfizer and BioNTech, including Pfizer-BioNTech COVID-19 Vaccine (2024-2025 Formula), have been authorized for emergency use by the FDA under an EUA to prevent COVID-19 in individuals aged 6 months of age and older. The emergency uses are only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of the medical product during the COVID-19 pandemic under Section 564(b)(1) of the U.S. Federal Food, Drug and Cosmetics Act, unless the declaration is terminated or authorization revoked sooner. Please see the EUA Fact Sheets atwww.covid19oralrx.com andwww.cvdvaccine-us.com.

This Form 10-K includes discussion of certain clinical studies relating to various in-line products and/or product candidates. These studies typically are part of a larger body of clinical data relating to such products or product candidates, and the discussion herein should be considered in the context of the larger body of data. In addition, clinical trial data are subject to differing interpretations, and, even when we view data as sufficient to support the safety and/or efficacy of a product candidate or a new indication for an in-line product, regulatory authorities may not share our views and may require additional data or may deny approval altogether.

Some amounts in this Form 10-K may not add due to rounding. All percentages have been calculated using unrounded amounts. All trademarks mentioned are the property of their owners.