Trial to Evaluate the Safety, Tolerability, and Immunogenicity of a Mosaic Hexavalent Influenza Vaccine VRC-FLUMOS0116-00-VP (FluMos-v2) in Healthy Adults

* INCLUSION CRITERIA: A subject must meet all of the following criteria: * Healthy adults between the ages of 18-50 years, inclusive * Based on history and physical examination, in good general health and without history of any of the conditions listed in the exclusion criteria * For Part A: Received at least one licensed influenza vaccine from 2018 through the 2022-2023 influenza season * Able and willing to complete the informed consent process * For Part A: Available for clinic visits for 40 weeks after enrollment, including through the 2023-2024 influenza season * For Part B: Available for clinic visits for 40 weeks after enrollment, including through the 2024-2025 influenza season * For Part B: Agrees to undergo four lymph node FNAs. * Able to provide proof of identity to the satisfaction of the study clinician completing the enrollment process * Physical examination and laboratory results without clinically significant findings and a Body Mass Index (BMI) \<= 35 within the 56 days before enrollment * For both Parts A and B: Agrees to not receive any licensed influenza vaccine during study participation due to potential confounding of study results * Willing to have blood samples collected, stored indefinitely, and used for research purposes * For Part B: Willing to have lymph node samples collected, stored indefinitely, and used for research purposes Laboratory Criteria within 56 days before enrollment * White blood cells (WBC) and differential within institutional normal range or accompanied by the site Principal Investigator (PI) or designee approval * Total lymphocyte count \>= 800 cells/microliter * Platelets = 125,000 - 500,000 cells/microliter * Hemoglobin within institutional normal range or accompanied by the PI or designee approval * Alanine aminotransferase (ALT) \<= 1.25 x institutional upper limit of normal (ULN) * Aspartate aminotransferase (AST) \<= 1.25 x institutional ULN * Alkaline phosphatase (ALP) \<1.1 x institutional ULN * Total bilirubin within institutional normal range or accompanied by the PI or designee approval * Serum creatinine \<= 1.1 x institutional ULN * Negative for HIV infection by an FDA-approved method of detection Criteria applicable to women of childbearing potential: * Negative beta-human chorionic gonadotropin (beta-HCG) pregnancy test (urine or serum) on the day of enrollment * Agrees to use an effective means of birth control from at least 21 days prior to enrollment through the end of the study for sample collection. EXCLUSION CRITERIA: A participant will be excluded if one or more of the following conditions apply: -Women breast-feeding or planning to become pregnant during the study Participant has received any of the following substances: * More than 10 days of systemic immunosuppressive medications or cytotoxic medications within the 4 weeks prior to enrollment or any within the 14 days prior to enrollment * Blood products within 16 weeks prior to enrollment * Live attenuated vaccines within 4 weeks prior to enrollment * Inactivated vaccines within 2 weeks prior to enrollment * Investigational research agents within 4 weeks prior to enrollment or planning to receive investigational products while on the study (Note: SARS-CoV-2 vaccines licensed and/or approved by emergency use authorization are not exclusionary, but are subject to the criteria for timing of inactivated vaccines or mRNA vaccines) * mRNA vaccines within 4 weeks prior to enrollment * Current allergy treatment with allergen immunotherapy with antigen injections, unless on maintenance schedule * Current anti-TB prophylaxis or therapy * Receipt of investigational ferritin-based nanoparticle influenza vaccines, with the exception of participants previously enrolled in the VRC 316 study as follows: Group 2 (HA-F A/Sing prime, HA-F A/Sing boost), 3A (DNA A/Sing prime, HA-F A/Sing boost) or 4A (HA-F A/Sing prime, HA-F A/Sing boost). * Receipt of the mosaic quadrivalent influenza vaccine VRC-FLUMOS0111-00-VP (FluMos-v1) * Receipt of any licensed influenza vaccine within 6 months prior to enrollment. * For Part A: Receipt of the 2023-2024 licensed influenza vaccine * For Part B: Plan to or are required to receive the 2024-2025 licensed influenza vaccine * For Part B: Receipt of any licensed seasonal influenza vaccine since the 2022-2023 influenza season; including the 2023-2024 influenza season through the 2024-2025 influenza season. Subject has a history of any of the following clinically significant conditions: * Serious reactions to vaccines that preclude receipt of the study vaccinations as determined by the investigator * Hereditary angioedema, acquired angioedema, or idiopathic forms of angioedema * Asthma that is not well controlled * Diabetes mellitus (type I or II), with the exception of gestational diabetes * Thyroid disease that is not well controlled * Idiopathic urticaria within the past year * Autoimmune disease or immunodeficiency * Hypertension that is not well controlled * Bleeding disorder diagnosed by a doctor (e.g., factor deficiency, coagulopathy, or platelet disorder requiring special precautions) or significant bruising or bleeding difficulties with IM injections or blood draws * Malignancy that is active or history of malignancy that is likely to recur during the period of the study * Seizure disorder other than 1) febrile seizures, 2) seizures secondary to alcohol withdrawal more than 3 years ago, or 3) seizures that have not required treatment within the last 3 years * Asplenia, functional asplenia or any condition resulting in the absence or removal of the spleen * Guillain-Barre Syndrome * Any medical, psychiatric, or social condition, occupational reason, or other responsibility that, in the judgment of the investigator, is a contraindication to protocol participation or impairs a subject s ability to give informed consent, including but not limited to clinically significant forms of infectious diseases, drug or alcohol abuse, autoimmune diseases, psychiatric disorders, or heart disease.