Can you still get infected with hepatitis B after receiving the hepatitis B vaccine?

Sep 03, 2025 Source: Cainiu Health

Dr. Gao Jun

Introduction

Hepatitis B usually refers to hepatitis B virus (HBV) infection, and the hepatitis B vaccine typically means the hepatitis B virus vaccine. Generally, whether one can still contract hepatitis B after receiving the hepatitis B virus vaccine depends on individual immune responses, exposure risks, and other factors. If discomfort occurs, such as fatigue, jaundice, or other symptoms, prompt medical attention is recommended.

HBV usually refers to hepatitis B, and the hepatitis B vaccine typically refers to the hepatitis B virus vaccine. Generally speaking, whether a person who has received the hepatitis B virus vaccine can still get infected with hepatitis B needs to be comprehensively evaluated based on individual immune responses and exposure risks. If discomfort occurs, such as fatigue or jaundice, timely medical attention is recommended. Detailed analysis is as follows:

If the vaccine recipient has a good immune response and sufficient titers of hepatitis B surface antibodies are produced in the body after completing the full vaccination schedule, and there is no high-risk exposure in daily life, infection with hepatitis B usually does not occur. In these individuals, the antibodies can effectively recognize and neutralize invading hepatitis B virus, forming a reliable protective barrier, with a very low probability of infection.

If the vaccine recipient has a poor immune response, such as due to older age or immunodeficiency, and no antibodies or insufficient antibody titers are produced after vaccination, or if there is very high-risk exposure despite having antibodies, there remains a possibility of hepatitis B infection. When antibody titers are insufficient, the protective capacity is weak and cannot fully resist viral invasion, making infection more likely to occur.

After vaccination, regular testing of hepatitis B surface antibody titers is necessary, and timely booster doses should be administered if titers are inadequate. In daily life, sharing needles, toothbrushes, or other items that may come into contact with blood should be avoided to reduce high-risk exposure. If an accidental exposure occurs, immediate medical consultation is required to implement emergency protective measures. Completing the full vaccination schedule according to guidelines is important to avoid incomplete vaccination affecting antibody production.

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What should you eat if you have mild hepatitis B (small three positives)?

In general, patients with "small three positives" (chronic hepatitis B with positive HBsAg, anti-HBe, and HBV DNA) should support liver health through diet while using medication to control the condition. Recommended foods typically include eggs, broccoli, sea bass, spinach, and oats. Commonly used medications include entecavir dispersible tablets, tenofovir disoproxil fumarate tablets, silybin capsules, compound glycyrrhizin tablets, and hepatoprotective tablets.

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How long can the second dose of the hepatitis B vaccine be postponed?

If the vaccination is postponed due to short-term unexpected situations such as a mild cold or temporary travel, it is sufficient to receive the missed dose within one month; there is no need to restart the entire vaccination series. The subsequent third dose should still be administered according to the originally planned interval and will generally result in normal production of effective antibodies. However, if the delay exceeds one month, especially beyond two months, the immune memory induced by the first vaccine dose may weaken.