Investor Presentaiton

Reactogenicity sanofi Sanofi's proprietary MIMIC® system to increase efficiency of mRNA screening Preclinical MIMIC Prediction Clinical Outcomes log2 fold-change in cytokines 50 40 40 30 20 20 10 0 2021 LNP 2 (Unmodified RNA) 87 Vaccines Investor Event LNP 2 (Modified RNA) 2023 LNP 3 (Modified RNA) Solicited Systemic Reactions (%) Solicited Systemic Reactions (%) comparator 100 ■Grade 1-2 80 ■Grade 3 60 40 20 0 rHA 40 20 ■Grade 1 ■Grade 2 ■Grade 3 Unmodified Dose Dose Dose Level 1 Level 2 Level 3 Modified IIV4 Modified Dose Dose Dose Dose Dose Level 1 Level 2 Level 3 Level 4 Level 5 0 LNP LNP LNP LNP 2 3 2 3 LNP LNP 2 3 LNP LNP LNP LNP LNP LNP 2 3 2 3 2 3 Fever Headache Chills Malaise Arthralgia Myalgia

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