Immunogenicity and Safety of Hecolin® in HIV Positive/Negative Adults and in Children

Inclusion Criteria (healthy participants only):

1. Healthy participants 2 to 45 years of age at enrollment,
2. Participants/Parent(s)/LAR who have voluntarily given informed consent/assent,
3. Participants/Parent(s)/LAR willing to follow the study procedures and available for the entire duration of the study and agrees to the collection of all biospecimens,
4. HIV negative,
5. Not pregnant,
6. Agreement to practice effective contraception for female participants of childbearing potential and non-sterile males until at least 8 months after the first vaccination.
7. Has practiced adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the first dose of vaccine, and
8. Female participant not currently breastfeeding.

Exclusion Criteria:

An individual who meets any of the following criteria will be excluded from participation in this study:

1. Has received any hepatitis E vaccine in the past,
2. Febrile illness (body temperature ≥ 38°C) or acute illness within 3 days prior to the study vaccination,
3. Known history or allergy to study vaccine components and/or excipients or other medications, or any other allergies or medical history deemed by the investigator to increase the risk of an adverse event if they were to participate in the trial (e.g., Guillain-Barre Syndrome),
4. Major congenital abnormalities which in the opinion of the investigator may affect the participant's participation in the study,
5. Known history of immune function disorders including immunodeficiency diseases (known HIV infection or other immune function disorders) and lupus,
6. Chronic use of systemic steroids (\>2 mg/kg/day or \>20 mg/day prednisone equivalent for periods exceeding 10 days), cytotoxic or other immunosuppressive drugs within the past 6 weeks,
7. Any abnormality or chronic disease which in the opinion of the investigator might be detrimental to the safety of the participant and interfere with the assessment of the study objectives,
8. Behavioral or cognitive impairment, chronic substance abuse, or psychiatric disease or neural disorders, that, in the opinion of the investigator, could interfere with the participant's ability to participate in the trial,
9. History of splenectomy,
10. History of thrombocytopenia and/or thrombosis, myocarditis or pericarditis or any other significant cardiac condition,
11. With a known bleeding diathesis or any condition that may be associated with a prolonged bleeding time resulting in contraindication for IM injections/blood extractions.,
12. Receipt of blood or blood-derived products in the past 3 months,
13. Receipt of other vaccines from 4 weeks prior to test vaccination or planned to receive any vaccine within 4 weeks of last dose of study vaccine,
14. Concomitantly enrolled or scheduled to be enrolled in another trial,
15. Research staff involved with the clinical study or family/household members of research staff,
16. Body mass index (BMI) of ≥ 40 in adults and for children a BMI- index-for-age is ≥95th percentile, at the time of the screening visit, or
17. As per the Investigator's medical judgement, an individual could be excluded from the study despite meeting all inclusion/exclusion criteria mentioned above.

Inclusion criteria for HIV-positive arm:

1. Adults 18-45 years living with HIV on anti-retroviral (ARV) treatment and willing to have CD4 and viral load measured as per protocol,
2. Able to provide a voluntary signed informed consent,
3. Participants willing to follow the study procedures of the study and available for the entire duration of the study and agrees to the collection of all biospecimens,
4. Agreement to practice effective contraception for female participants of childbearing potential and non-sterile males until at least 3 months after the last vaccination.
5. Has practiced adequate contraception or has abstained from all activities that could result in pregnancy for at least 28 days prior to the last dose of vaccine, and
6. Female participant is currently not breastfeeding.

Exclusion Criteria for HIV-positive arm:

An individual who meets any of the following criteria will be excluded from participation in this study:

1. Has received any hepatitis E vaccine in the past,
2. Newly diagnosed HIV-positive (diagnosed on screening) on ARVs for 0-4 weeks (Note: These participants can be re-screened and enrolled once they have been on ARVs for 4 weeks),
3. Febrile illness (body temperature ≥ 38°C) or acute illness within 3 days prior to the study vaccination,
4. Serious adverse reaction to any vaccine, or any component of the investigational vaccine, including a history of anaphylaxis and symptoms of a severe allergic reaction and history of allergies in the past,
5. Current hospitalization,
6. History of inherited blood disorders, heparin-induced thrombocytopenia, or thromboembolic disorders,
7. History of any blood product transfusion up to 6 months before enrolment,
8. Receipt of other vaccines from 4 weeks prior to test vaccination or planned to receive any vaccine within 4 weeks of last dose of study vaccine
9. Currently taking anti-coagulation therapy, or chronic aspirin in the past 3 months,
10. Pregnant or breastfeeding women throughout the study period,
11. Extreme obesity (defined as BMI of 40 kg/m2 or higher),
12. Chronic kidney disease requiring dialysis,
13. Liver disease (Note mild chronic liver disease is not an exclusion criterion),
14. Participants with acquired or hereditary immunodeficiencies other than HIV,
15. History of hereditary, idiopathic, or acquired angioedema,
16. No spleen or functional asplenia,
17. Platelet disorder or other bleeding disorder that may cause injection contraindication,
18. Chronic use (more than 14 continuous days) of any medications that may be associated with impaired immune responsiveness including, but not limited to, systemic corticosteroids exceeding 10 mg/day of prednisone equivalent, allergy injections, immunoglobulin, interferon, or immunomodulators. The use of low dose topical, ophthalmic, inhaled, and intranasal steroid preparations will be permitted,
19. According to the judgement of the investigator, the participant has any other factors that might interfere with the results of the clinical trial or pose additional risk due to participation in the study,
20. Assessed by the Investigator to be unable or unwilling to comply with the requirements of the protocol