Based on the new study published in The Lancet Neurology, it was found that childhood vaccination is related with earlier onset of the neurological condition called Dravet syndrome.
In the past, pertussis vaccine which was routinely given to children together with diphtheria and typhoid (DTP) vaccines had been associated with vaccine encephalopathy.
Proposed associations between childhood vaccination and neurological conditions have always raised controversy and compromised vaccination uptake.
Out of 14 patients with vaccine encephalopathy, 12 were found to have Dravet syndrome according to the study conducted by Dr Samuel Berkovic and colleagues from the Epilepsy Research Centre, University of Melbourne. The condition was associated with mutations of the sodium channel gene SCN1A in 11 of the 12 affected children.
In the determination of the link between DTP vaccination and the onset of Dravet syndrome and in the study to check whether the vaccination affects time of onset or the clinical outcome of the disorder, researchers studied a total of 40 patients with Dravet syndrome retrospectively.
The group of patients was selected based on their SCN1A mutations, a first seizure that was a convulsion, certified medical and vaccination records and not due to any temporal link of seizures from vaccination.
Within two days of vaccination, there is an increase in the number of patients who experienced seizure. The children were then separated into two groups, based on whether they had the seizure on the same day (vaccination-proximate) or the day after (vaccination-distant).
In the first group (vaccination-proximate), the average age at seizure onset was significantly lower (18.4 weeks) than the vaccination-distant group which was at 26.2 weeks.
Both groups showed no differences in the intellectual outcome, subsequent seizure type, or gene mutation type. Additional study found that intellectual outcome did not vary between patients receiving vaccine after seizure onset and those who did not.
The study authors said childhood vaccination is a sensitive issue where science, societal views and social policy are poorly aligned sometimes, rephrasing the respected views made by Professor Simon Shorvon (UK) and Anne Berg (USA).
According the authors, vaccinations may trigger earlier onset of Dravet syndrome in children because of the SCN1A mutation, of which they are predisposed to develop the condition.
However, vaccination should not be withheld from children with SCN1A mutations because we found no evidence that vaccinations before or after the disease onset affect outcome, concluded the authors.