2.2. Study Protocol
coin toss
Initially this study was designed to recruit participants who has recently tested positive for COVID-19 (within the prior 10–15 days) and were unvaccinated. However, in December of 2020, the Pfizer-BioNTech COVID-19 vaccine was made available under emergency use authorization by the US Food and Drug Administration (FDA) [This study followed a randomized placebo-controlled parallel arm trial design. Participants were randomized by coin toss to receive the active ingredient dietary supplement or placebo for four weeks. Randomization was carried out by a blinded research team member who was not involved in data collection. Participants interested in the study were initially screened for eligibility via an online survey. Those who met inclusion criteria per the online screener were interviewed by phone to confirm eligibility. Eligible participants were scheduled to visit the test site (ISTB8 Phoenix Biomedical Collaborative Building; Phoenix, AZ, USA). The study participants visited the test site twice during the study period, at baseline and week 4. Study measures conducted during the baseline visit were repeated at week 4. During study visits, participants completed a standard health history questionnaire and were led through a multiple pass 24-h dietary recall by trained study staff. Study staff blinded to participant group assignment analyzed data from diet recalls using The Food Processor