Can You Get Hepatitis B from Infected Individuals After Vaccination?

Hepatitis B

Hello, doctor: I would like to ask, if someone has previously received the hepatitis B vaccine, will they still be at risk of contracting the virus from contact with a person who has hepatitis B? Also, how long do the antibodies produced by the vaccine last in the body?

Xiao Ling, 20~29 year old female. Ask Date: 2007/09/30

Dr. Xiao Jingqin reply Internal Medicine

First, it should be confirmed whether there are hepatitis B surface antibodies present.
A positive result indicates immunity and that infection will not occur.
Additionally, the type of contact you mentioned, such as sharing food, does not transmit the virus.
Hepatitis B virus is transmitted through blood and bodily fluids, such as through sexual contact or other intimate interactions.
If an individual is confirmed to have no antibodies, there is a possibility of transmission.
Currently, the hepatitis B vaccination consists of three doses, and the likelihood of developing hepatitis B antibodies exceeds 90%.
The antibodies generally last for 10 to 15 years.
It has been observed that individuals who have completed the full three-dose vaccination may have undetectable or diminished antibody levels, yet they are still unlikely to be infected by the hepatitis B virus.

Reply Date: 2007/09/30

More Info

Vaccination against Hepatitis B is a highly effective method for preventing infection from the Hepatitis B virus (HBV). If you have received the complete series of the Hepatitis B vaccine, which typically consists of three doses administered over a six-month period, and have subsequently tested positive for Hepatitis B surface antibodies (Anti-HBs), you are considered protected against the virus. This means that even if you come into contact with an individual who is infected with Hepatitis B, the likelihood of contracting the virus is significantly reduced.

The Hepatitis B vaccine works by stimulating your immune system to produce antibodies against the virus. These antibodies provide a protective response, enabling your body to fight off the virus if you are exposed. The presence of Anti-HBs in your blood indicates that your body has successfully developed immunity to the virus. In general, individuals who have developed these antibodies are at a very low risk of becoming infected, even if they are exposed to the virus through contact with infected blood or bodily fluids.

However, it is important to note that the immunity provided by the vaccine may not be lifelong. Studies suggest that while the antibodies can persist for many years, their levels may decline over time. For most individuals, protective antibody levels remain sufficient for at least 5 to 10 years after vaccination. In some cases, especially in older adults or those with compromised immune systems, the antibody levels may wane more quickly. Therefore, it is advisable to check your antibody levels periodically, especially if you are at higher risk of exposure to Hepatitis B.

If you have not been tested for your antibody levels after completing the vaccination series, it may be beneficial to do so. A simple blood test can determine whether you still have adequate levels of Anti-HBs. If your levels are found to be low or undetectable, a booster dose of the vaccine can be administered to help restore your immunity.

In terms of exposure risk, while the vaccine significantly reduces the chance of infection, it is not 100% foolproof. If you have a significant exposure to infected blood (for example, through a deep cut or puncture wound), it is recommended to seek medical advice. In some cases, post-exposure prophylaxis (PEP) may be indicated, especially if the exposure is deemed high-risk and you have not been vaccinated or your immunity is uncertain.

In summary, if you have been vaccinated against Hepatitis B and have confirmed the presence of protective antibodies, your risk of contracting the virus from an infected individual is very low. However, it is prudent to monitor your antibody levels over time and consult with a healthcare provider if you have concerns about potential exposure or if you are due for a booster vaccination. Regular check-ups and awareness of your vaccination status are key components in maintaining your health and preventing Hepatitis B infection.

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