The study is designed to assess whether selenium supplementation can boost the immunity response to influenza vaccination in healthy adults. This is a randomized, prospective study enrolling a total of 60 healthy subjects, 18-55 years old.

Background: Selenium is an essential trace element required for human health and wellbeing. Despite mouse studies and human clinical trial suggest selenium supplementation might enhance immunity, little is known for the effects of selenium supplementation on humoral immunity. Vaccination is the most effective medical intervention to prevent infections and to reduce disability and mortality associated with infectious disease. However, some individuals, in healthy or disease conditions, mount less effective humoral immune responses to vaccination. Therefore, new strategy to enhance humoral immunity upon vaccination is highly sought after. Using mouse models, we have observed that selenium supplementation significantly increased antigen-specific antibody responses. Thus, we hypothesize that selenium supplementation may be beneficial in enhancing humoral immunity in humans.

Objectives: To investigate whether selenium supplementation will boost the humoral response to influenza vaccination in healthy adults.

Design and trial size: This is a randomized prospective study. A total of 60 healthy subjects, 18-55 years old, will be enrolled in this study.

Intervention and duration: The enrolled subjects will be randomized into selenium supplementation and control group. The selenium supplementation group will receive 200 μg selenium daily by taking two selenium-enriched yeast tablets (SelenoPrecise®, Pharma Nord) once daily for 60 days. The control group will not receive selenium supplementation. Thirty days after allocation, both groups will receive standard seasonal influenza vaccination for the 2019-2020 season. Peripheral blood samples will be collected at baseline (day 0, prior to treatment), day 30, day 37 (7 days after vaccination) and day 60 (30 days after vaccination).

Inclusion Criteria:

18-55 years, healthy subjects

Exclusion Criteria:

1. With the history of selenium supplementation as taking supplementation products or living more than 2 years in selenium-enriched area;
2. Had the symptoms of selenium toxicity or serum selenium level greater than 328 μg/L;
3. With the history of the administration of influenza vaccine in past three years or allergic to influenza vaccine;
4. With any current immunologic disorders, including autoimmune and allergic diseases;
5. With any cardiovascular, metabolic, mental, or psychological disorders;
6. Pregnancy or breastfeeding;
7. With the history of infectious diseases including airway infections in past three months;
8. Who are currently participating in other clinical studies or who have participated in other clinical research within 90 days