OUR PURPOSE PIONEERING SCIENCE 135 GRI CONTENT INDEX BIOGEN 2021 YEAR IN REVIEW PATIENTS OUR PEOPLE ENVIRONMENT COMMUNITY REPORTING GRI indicator Reporting Requirements 2021 Response Alignment SDG 102–44 Key topics and concerns that have been raised through stakeholder engagement, including: • How the organization has responded to those key topics and concerns, including through its reporting. • The stakeholder groups that raised each of the key topics and concerns. Patients and Reporting – 2021 Year in Review Reporting practice 102–45 a. A list of all entities included in the organization’s consolidated financial statements or equivalent documents. b. Whether any entity included in the organization’s consolidated financial statements or equivalent documents is not covered by the report. Item 1., Business, 2021 Annual Report All major entities are included in the boundaries of this report. 102–46 a. An explanation of the process for defining the report content and the topic Boundaries. b. An explanation of how the organization has implemented the Reporting Principles for defining report content. Additional requirements for compiling: When compiling the information specified in Disclosure 102–46, the reporting organization shall include an explanation of how the Materiality principle was applied to identify material topics, including any assumptions made. Reporting – 2021 Year in Review 102–47 A list of the material topics identified in the process for defining report content. Reporting – 2021 Year in Review * 102–48 The effect of any restatements of information given in previous reports, and the reasons for such restatements. Restatements for previous disclosed metrics are identified in the ESG Data Table . 102–49 Significant changes from previous reporting periods in the list of material topics and topic Boundaries. Biogen conducted an ESG materiality assessment in 2021. The results inform the topic boundaries of this report and can be found in the Reporting section of this 2021 Year in Review. 102–50 Reporting period for the information provided. Data cover fiscal year ending Dec. 31, 2021 (Some activities from 2022 are also included). 102–51 If applicable, the date of the most recent previous report. April 23, 2021 102–52 Reporting cycle. We report on an annual basis. 102–53 The contact point for questions regarding the report or its contents. Biogen Reputation contact: [email protected] Responsibility contact: [email protected] 102–54 The claim made by the organization, if it has prepared a report in accordance with the GRI Standards, either: • ’This report has been prepared in accordance with the GRI Standards: Core option’. • ’This report has been prepared in accordance with the GRI Standards: Comprehensive option’. This report has been prepared in accordance with the GRI Standards: Core option / Alignment option.