Vaccination And Brain Damage: The Transition of DTP to DTaP

You would have received immunisation for Pertussis at a very young age. The vaccine comes as a combination of immunisation towards Diphtheria, Tetanus and Pertussis ( whooping cough, caused by Bordetella Pertussis ). Thus, the vaccine was referred to as the DTP vaccine.

The P stands for Pertussis. Initially, the Pertussis vaccine was administered as a whole cell. Meaning, we introduce units of inactivated bacteria or viruses as a whole, complete in structure. This will provide the full set of antigens a pathogen can possess.

However, the whole-cell Pertussis vaccine can damage the myelin sheath. This can cause encephalopathy. This is why the DTP vaccine was administered before the age of 2. The myelin sheath develops at the age of 2.

So the idea was to have your child vaccinated with DTP before the myelin sheath develops so as to prevent brain damage. However, not everyone is compliant with the vaccination schedule.

Scenario:

Mr X has a child with a missed DTP vaccine, which was scheduled before the age of 2. The child is now 3 years old. He visits a healthcare centre for the vaccine. The healthcare personnel administers the vaccine which induces active immunisation. By the same token, damage to the myelin sheath also occurs. The child then develops encephalopathy.

Solution:

The illustrated scenario is not something uncommon. We saw this pattern of not adhering to the vaccination schedule during our recent pandemic too. This is why DTP transitioned to DTaP. The whole cell vaccine was changed to acellular vaccine ( therefore, aP ). An acellular vaccine contains only components of the bacteria and detoxified toxins, rather than the whole structure.

The acellular Pertussis vaccine is not harmful to the myelin sheath.

That is a brief story on why DTP became DTaP.

courtesy: As mentored by acharya Prof. Dr. P.K Rajesh M.B.B.S, MD

Image: Prof Rajesh & Me