* 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.