Q. 1. Is there very small but definite risk of CJD (Crutzfeldt-Jacob disease) and Bovine Spongiform Encephalopathy (BSE) with plasma derived, hepatitis vaccine? One swadeshi genetically engineered hepatitis B vaccine (Shanvac B) is equal in cost or even cheaper than other similar vaccines, so what should be the first choice for this vaccine now?

Q. 2. Does the IAP recommend a neonatal ,dose of 5 µg, as one plasma derived vaccine supplier claims?

Bipin Kumar,
Dak Bungalow Road,
Bishanpur, Begusarai,
Bihar, India.

Creutzfeldt-Jakob disease (CJD) and its variants are believed to be caused by the newly recognized Prion agent (proteinaceous infectious particle), a protein that defies destruction by ordinary processes of disinfection and sterilization. The agent causes neurodegenerative diseases, which may be due to the transmission of the Prion agent or its sporadic and spontaneous development in some individuals. The pathology is spongiform encephalopathy. It may occur across many species and the disease in cattle is called bovine spongiform encephalopathy and in sheep, scrapie.

This Prion agent is found in the brain of affected animals or persons and it is transmitted by oral and parenteral routes. There is so far no evidence that it is present in transmissible form in the blood or blood derivatives of humans. Had it not been so, all those who have ever received blood transfusion or blood products such as gammaglobulin, plasma factors or albumin would have been at some risk of Prion disease. There has been no evidence to suggest that there is any-risk of transmission through them. Therefore, hepatitis B vaccine derived from human plasma is also safe. No one can predict if this situation will change in future. Sheep offal fed to cattle was the origin of the epizootic of bovine spongiform encephalopathy (popularly called mad cow syndrome) in the UK. There have been a few cases of an illness in humans, believed to be caused by transmission from the bovine. In other words, the scenario of infectious disease do keep changing and having seen the appearance and progression of human immunodeficiency virus infection, no one will venture to predict that everything will continue as they are today.

The ideal thing is not to fall sick, and if one does, not to receive blood transfusion if it was not life-saving at the time. I foresee a time when blood transfusions will be rare and the factors from the plasma fraction are genetically engineered and produced in some vector cells. Hepatitis B vaccine has been its forerunner in that it can be derived from plasma or made in yeast cells. While plasma derived vaccine is completely safe, I would not expect any manufacturers producing and marketing it in another 10 years or so. But today, it is safe, effective and less expensive and we should continue using it for these qualities. In future, recombinant products will also become as low priced as plasma derived product, and indeed cheaper since we can upscale production at will. If genetically engineered vaccine of good quality is available at lower prices than its competitors, then that will certainly be a factor in its favor, particularly for a national routine immunization program. The first choice of vaccine is not for me to make for some one else, but for each person to make for oneself, taking all information into consideration. All licensed vaccines against hepatitis B are safe and effective.

The choice for the dose of vaccine for the neonate as 5 or 10 µg is not a decision to be made by preference, but by data. Manufacturers stipulate the dose of their product based on the results of extensive studies and any change must be made by specific studies only. The only exception to this guideline I will suggest is not to use a vaccine for which 2.5 µg has been stipulated for the neonate. Fortunately such a product is not marketted in India al- though available elsewhere.
 

T. Jacob John,
Chairman,
Committee on Immunization and
President, Indian Academy of Pediatrics,
2/91 E2 Kamalakshipuram,
Vellore, Tamil Nadu 632 002,
India.