Moderna’s therapeutics: Propionic acidemia (PA) (mRNA-3927) Last program update: September 9, 2021

Preclinical Moderna Modality Program ID # Phase 1 Phase 2 Phase 3 Commercial development rights Antibody against Chikungunya Worldwide virus mRNA-1944 DARPA funded IL-2 Worldwide Systemic Autoimmune disorders mRNA-6231 secreted & cell Relaxin Worldwide surface Heart failure mRNA-0184 therapeutics PD-L1 Worldwide Autoimmune hepatitis mRNA-6981 Personalized cancer vaccine 50-50 global profit mRNA-4157 sharing Cancer (PCV) with Merck vaccines 50-50 global profit KRAS vaccine mRNA-5671 sharing with Merck OX40L/IL-23/IL-36γ (Triplet) Worldwide Intratumoral Solid tumors/lymphoma mRNA-2752 Immuno- 50-50 U.S. profit oncology IL-12 sharing; AZ to pay Solid tumors MEDI1191 royalties on ex- U.S. sales Localized VEGF-A AZ to pay Regenerative AZD8601 milestones and Myocardial ischemia royalties Therapeutics Propionic Acidemia (PA) mRNA-3927 Worldwide

Methylmalonic Acidemia (MMA) mRNA-3705 Worldwide Systemic Glycogen Storage Disease Type Intracellular Worldwide 1a (GSD1a) mRNA-3745 Open IND Therapeutics (PKU) mRNA-3283 Worldwide Crigler-Najjar Syndrome Type 1 Provided to ILCM (CN-1) mRNA-3351 free of charge

Slide 1 PA therapy (mRNA-3927) encodes for an intracellular

▪ Propionic Acidemia (PA) is a rare Mitochondrion ̶ Affects 1/20,000 to 1/250,000 individuals in various regions of the world Odd-chainfattyacids ▪ Changes in the PCCA and PCCB cause propionic Propionicacid Cholesterol esters acidemia (intestinal flora) Propionylcarnitine Propionyl-CoA 3-OH-propionate ̶ These genes provide instructions for making two parts 2-methylcitrate (subunits) of the propionyl-CoA carboxylase Propionic Acidemia ̶ Change in the PCCA or PCCB disrupt the function PCC enzyme Active PCC of the enzyme and prevent the normal breakdown of deficiency enzyme these molecules ▪ As a result, a substance called propionyl-CoA and other potentially harmful compounds can build up to toxic levels Moderna’s mRNA therapy for PA (mRNA- in the body; buildup damages the brain and nervous 3927) encodes for two proteins that form the system, causing the serious health problems associated with deficient enzyme propionic acidemia • PCCA (PA Type I) • PCCB (PA Type II)

Slide 2 https://rarediseases.org/rare-diseases/propionic-acidemia/ Propionic acidemia (PA) has significant morbidity and mortality and is without any approved therapies

PA Clinical Manifestations ▪ Primarily a pediatric disease with majority of cases presenting ▪ Recurrent episodes of life-threatening metabolic decompensations within 3 days of life, untreated may lead to coma and death ▪ Progressive multi-organ damage ̶ Brain damage ̶ Seizures ▪ Treatment: There is no approved ̶ Intellectual disability therapy for PA ̶ Inflammation of the pancreas (pancreatitis) ̶ Standard of care included ̶ Chronic renal failure dietary and palliative ̶ Heart failure (cardiomyopathy); heart rhythm problems measures ̶ Increased risk of having a metabolic stroke as early as a few weeks of age ̶ Liver transplant has been ̶ Osteoporosis which can lead to fractures shown to improve ̶ Hematologic: reduced number of cells in (anemia, biochemical and clinical leukopenia, thrombocytopenia, pancytopenia) outcomes ̶ Growth retardation ̶ Severe vision problems

Slide 3 mRNA-3927 is a combination therapy encoding for PCCA and PCCB protein to form an active PCC enzyme (uses IV-LNP 1)

Mitochondrial matrix Formulation Propionyl-CoA Biotin Methylmalonyl-CoA carboxylase PCCA-encoded (PCC enzyme) mRNA dodecamer PCCB-encoded mRNA Active enzyme

Liver Liver

Propionyl-CoA

Liver cell

Protein chain Ribosome PCCA subunit

Mitochondria

PCCB subunit

Encoded mRNAs Endoplasmic Reticulum Cytosol Nucleus

Slide 4 Propionic acidemia (PA) ongoing in Phase 1/2 study

Key objective ▪ To evaluate the safety and pharmacology of mRNA- 3927 in patients 1 year of age and older with propionic Paramount study ongoing acidemia (PA)

Primary endpoint ▪ Safety ▪ Pharmacokinetics and Pharmacodynamics

Secondary endpoint ▪ Incidence and severity of adverse events (AEs) ▪ Change in plasma biomarkers: methylcitric acid (2-MC) and 3-Hydroxypropionic acid (3-HP)

Trial progress ▪ Phase 1/2 enrolling patients

Slide 5 Propionic acidemia (mRNA-3927) Phase 1/2 Paramount Study

Dose Optimization Stage (up to 5 cohorts)

3 more participants may be enrolled in Patient cohort to further enrolled characterize safety ▪ Adaptive trial design 3 participants 1 dosed ▪ Recruiting patients in Canada, Dose Expansion United Kingdom and Stage 21-day DLT (4 to 6 new observation Open new M4 participants)2 ▪ Multiple patients dosed; completed cohort window after dose 1 for each enrollment of cohort 1 participant

PK/PD modeling ▪ Looking for plasma biomarkers and safety data (methylcitric acid (2-MC) and 3- review after Hydroxypropionic acid (3-HP)) each cohort is Dose Selected fully enrolled

DLT = dose-limiting ; PD = pharmacodynamic(s); PK – pharmacokinetic(s) 1. The first 2 participants will be ≥ 8 years of age 2. In the dose expansion stage, a minimum of 2 participants with each subtype (PCCA and PCCB) will be Slide 6 enrolled Forward-looking statements

This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended including, but not limited to, statements concerning potential development candidate applications, development candid ate activities, preclinical and clinical studies, regulatory submissions and approvals, risk management and estimates and forward -looking projections with respect to Moderna or its anticipated future performance or events. In some cases, forward -looking statements can be identified by terminology such as “may,” “should,” “expects,” “intends,” “plans,” “aims,” “anticipates,” “believes,” “estimat es,” “predicts,” “potential,” “continue,” or the negative of these terms or other comparable terminology, although not all forward -looking statements contain these words. The forward-looking statements in this presentation are neither promises nor guarantees, and you should not place undue reliance on these forward-looking statements because they involve known and unknown risks, uncertainties and other factors, many of which are beyond Moderna’s control and which could cause actual results to differ materially from those expressed or implied by these forward - looking statements. These risks, uncertainties and other factors include, among others: preclinical and clinical development is lengthy and uncertain, especially for a new category of medicines such as mRNA, and therefore Moderna’s preclinical programs or development candidates may be delayed, terminated, or may never advance to or in the clinic; no mRNA drug has been approved in this new p otential category of medicines, and may never be approved; mRNA drug development has substantial clinical development and regulatory r isks due to the novel and unprecedented nature of this new category of medicines; and those described in Moderna’s most recent Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (SEC) and in subsequent filings made by Moderna with SEC, which are available on the SEC's website at www.sec.gov. Except as required by law, Moderna disclaims any intention or responsibility for updating or revising any forward-looking statements in this presentation in the event of new information, future developments or otherwise. These forward-looking statements are based on Moderna’s current expectations and speak only as of the date hereof.

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