Question
Why do some doctors say that Hepatitis B antibodies are lifelong, while others say that a booster shot is needed every four or five years? Additional question: How can one determine the level of their antibodies, and at what level should reinforcement be considered?
Answer
A 15-year follow-up study in children from Long’an County, Guangxi, China, who were vaccinated with the Hepatitis B vaccine showed that the positive rate of Hepatitis B surface antigen in the vaccinated group was 1.9%, compared to 16.7% in the control group, with a protection rate of 88.6%. At 15 years, 50.9% of the vaccinated group had positive Hepatitis B antibodies. This indicates that the immunity of the Hepatitis B vaccine can last up to 15 years. Similar reports have also been published internationally. In Senegal, Africa, 12 years after vaccination with the Hepatitis B vaccine, the positive rate of Hepatitis B surface antigen in the vaccinated group was 2%, compared to 19% in the control group, with a protection rate of 88%. Among children vaccinated with the Hepatitis B vaccine, 68% had Hepatitis B antibodies. After vaccination, although antibody levels decrease year by year due to time passing, they can rise again when attacked by the Hepatitis B virus due to immune memory. This is particularly evident in high-incidence and high-risk populations. Therefore, overall, if a person has received the full course of Hepatitis B vaccine and has developed high-titer Hepatitis B antibodies, they may not need to be revaccinated within 10 years. However, on an individual basis, each person’s situation may differ, and specific analysis should be made for each case. For example, the latest national survey on Hepatitis B vaccine coverage rates shows that the rate of full-course qualified vaccination in China is only 28.4%, with 73.6% receiving non-full-course vaccination. Children who have not received full-course vaccination may not have Hepatitis B antibodies or may have low antibody titers. For such children, it is necessary to test for Hepatitis B antibodies. If antibodies are not produced or have disappeared, they should be revaccinated promptly. It is worth noting that even after receiving full-course Hepatitis B vaccination, there is still a 5% to 10% chance of not developing antibodies.