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What are the risks of vaccinating an infant with not fully developed brain barrier?

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Posted on Mon, 26 May 2014
Question: Hi, can you please tell me at what age the blood-brain barrier is fully developed and what the risks are of vaccinating an infant before it is fully developed? Thank you.
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Answered by Dr. Sudhir Kumar (39 minutes later)
Brief Answer:
Blood brain barrier is developed at six weeks age.

Detailed Answer:
Hi,

Thank you for posting your query.

I appreciate your query on an important topic. Blood brain barrier (BBB) exists in most newborn babies at the time of birth, as it's development is sort of complete at 28 weeks of gestation (before birth itself). However, some components of BBB are missing at birth and so it is immature. The complete development is seen in most infants by six weeks after birth.

This means that if vaccines are given prior to six weeks, it may cross the BBB resulting in brain damage. Earlier, mercury contained in hepatitis B vaccines used to cross BBB and may have resulted in increased cases of autism. Similarly, other vaccines such as DPT, HiB and polio vaccines could also cross BBB and cause brain damage or the actual infections (in case of live vaccines such as polio).

If the infants are immunised after six weeks, we do not expect any problem.

I hope it helps. Please get back if you have any follow up queries.

Best wishes,
Dr Sudhir Kumar MD DM (Neurology) XXXXXXX Consultant Neurologist
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Dr. Sudhir Kumar

Neurologist

Practicing since :1994

Answered : 6147 Questions

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What are the risks of vaccinating an infant with not fully developed brain barrier?

Brief Answer: Blood brain barrier is developed at six weeks age. Detailed Answer: Hi, Thank you for posting your query. I appreciate your query on an important topic. Blood brain barrier (BBB) exists in most newborn babies at the time of birth, as it's development is sort of complete at 28 weeks of gestation (before birth itself). However, some components of BBB are missing at birth and so it is immature. The complete development is seen in most infants by six weeks after birth. This means that if vaccines are given prior to six weeks, it may cross the BBB resulting in brain damage. Earlier, mercury contained in hepatitis B vaccines used to cross BBB and may have resulted in increased cases of autism. Similarly, other vaccines such as DPT, HiB and polio vaccines could also cross BBB and cause brain damage or the actual infections (in case of live vaccines such as polio). If the infants are immunised after six weeks, we do not expect any problem. I hope it helps. Please get back if you have any follow up queries. Best wishes, Dr Sudhir Kumar MD DM (Neurology) XXXXXXX Consultant Neurologist