Plain-English translation of NCT04970836 on ClinicalTrials.gov ↗ · Source last updated · Translation generated · How we translate trials
Read our Hepatitis B research guide →This study doesn't follow the usual testing phases — it may be an observational study or a different type of research.
This trial is studying hepatitis B booster vaccinations for young adults in Taiwan who were vaccinated as babies but no longer have protective antibodies. The study will compare whether one dose or two doses of the Engerix-B hepatitis B vaccine works better to restore protection, depending on how low your antibody levels currently are. By following 240 participants over a year and measuring antibody responses at different time points, researchers hope to give clearer guidance on how many booster shots people like you actually need.
Some people who received hepatitis B vaccines as infants lose their immunity over time and are at risk if exposed to the virus. Doctors aren't sure whether these young adults need one booster shot or two to get their protection back, especially if their current antibody levels are very low.
You likely qualify if…
You likely don't qualify if…
You will be randomly assigned to one of four groups based on your current antibody level and whether you receive one or two booster shots. If you get two doses, they will be given 28 days apart. Over the next 12 months, you'll have your blood drawn at five time points (baseline, 7–10 days after vaccination, 28 days, 24–28 weeks, and 48–52 weeks) to measure how well your immune system responds to the medication and whether your antibody protection returns.
AI-generated summary from trial data · Jun 18, 2026 · Not medical advice
Taiwan
Sponsor
National Taiwan University Hospital
Collaborators
Academia Sinica, Taiwan, Ministry of Science and Technology, Taiwan
Enrollment target
~240 participants
Started
August 2021
Primary completion
December 2027
Age range
20 Years – 36 Years
Last updated on clinicaltrials.gov in March 2025.
Reach out to the team running this trial. Response times vary — some teams are faster than others.
Central contact
CHYI-FENG JAN, MD, PHD
National Taiwan University Hospital
Tell us you're interested and we'll help connect you with the research team. We'll walk you through what to expect first — no email needed to get started.