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Immunization Dialogue |
Indian Pediatrics 2000;37: 105-107 |
Should Hib Vaccine be Given Priority Over Hepatitis B Vaccine |
Although horizontal transmission from person-to-person can occur, but, the chances of infants and young children getting infected in this manner are rare. On the other hand H. influenzae infection, being air-borne can occur at any time. The antibody level following Hepatitis B vaccination, in older infants and children are higher than in infants who are immunized at birth(1). We should administer Hepatitis B vaccine at birth only to the babies born to mothers who are suffering from Hepatitis B disease, and other infants be given Hib vaccine first and Hepatitis B vaccine later so that the children are protected against Hib infection and a better antibody level is achieved by administering Hepatitis B vaccine during later part of infancy. Yash Paul, Reference 1. Desai SP, Cherian T, Jacob John T. Hepatitis `B' Virus Infection. Indian Pediatr 1997; 34: 762-763. Reply Dr. Yash Paul has brought out some of the issues that the members of the Committee on Immunization have to grapple with, before the Committee makes its recommendations. Hepatitis B virus infection does not cause overt disease during infancy and early childhood. On the other hand, Haemophilus influenzae type b infection may invade tissues and cause menin- gitis, pneumonia or other pyogenic diseases in infancy and early preschool age. Yet, according to Academy policy, HB vaccine should be given to all infants, preferably starting from within 12 hours of birth. On the other hand, Hib vaccine is optional, and if chosen to be given, to be given preferably at 6, 10 and 14 weeks of age. Dr. Yash Paul asks why those infants whose mothers are not HB virus carriers should be given HB vaccine so early, which he alleges to be not the optimum age for best antibody levels to be obtained. Secondly, why should Hib vaccine not be offered to these infants, who can wait without detriment for their HB vaccine at a later age. The major problem here is to be judicious about the choice of vaccines, when there are several vaccines to choose from, the epidemio-logical need for them are not completely transparent, and they cost more than what poor families can afford. If our governments (central and/or state) were rich or wise enoguht to budget for all the new vaccines that are licensed in India, for all children, our job would have been simply to make an optimum immunization schedule accommodating all of them. This is the situation in the United States of America, where MMR vaccine, HB vaccine, Hib vaccine, and Varicella vaccine are woven into a complex immunization schedule. Moreover, instead of OPV, they give IPV, further increasing the number of injections due to the infant and young child. In the USA, the disease burdens and the economic loss due to these vaccine preventable diseases have been assessed before they were introduced in the routine immunization schedule. They give free vaccines to only the poorer sections of society, whereas the richer sections pay for the vaccines directly or through health insurance schemes. As a result of such broad based immunizations, the nation saves huge amounts of money annually. We have little or no epidemiological data, no health economic assessment of diseases and their prevention, and our health ministry assumes that the nation cannot afford to give these vaccines to all children, without calculating the immense economic gain the country will actually make if such diseases are prevented. It is under these circumstances that the IAP has to make choices of newer vaccines for routine use versus optional use. There are data to show that the national average of HB virus carrier rate is between 4 and 5 per cent. The major factor in carrier state is the acquisition of infection perinatally (vertical) or in infancy and early childhood (horizontal transmission). Using data from other countries, we can estimte that about one-fourth (at least) of them will develop chronic progressive liver disease such as chronic hepatitis, cirrhosis or hepatic carcinoma. In short, as much as one person out of every hundred is destined to die from HB disease as adult, which is eminently preventable, not in the present adult cohort, but in the growing generation. It is the (ethical, moral, epidemio-logical, scientific and economic) duty of the nation to offer this advantage to the adults of tomorrow, for they are today our children, tomorrow our future. The Academy has led the way and mandated the policy that all pedia-tricians try to immunize all infants, starting at birth, if at all possible. It is very unfortunate that our democratic governments, no matter what their political philosophies, are male dominated, and like in many families, pay very little attention to the prevention of illnesses in our own children. As members of the Academy it is our duty to make it easier for all our clients to take HB vaccine, by reducing the cost as much as we can manage. Using multi-dose vials, using the least expensive product, charg-ing no professional fee, are the ways we can try to achieve this. Hib infection is transmitted via respiratory route and we cannot predict which child would have invasive Hib disease, unlike the situation with HB infection, in a manner of speaking. If we tested all pregnant women for HB virus carrier state, we could predict the probability of vertical transmission. If we tested all family members, we could identify those families in which children have the risk of horizontal infection. These are not practical propositions and therefore the recommendation for routine prevention. The best estimate for the risk of Hib meningitis is about one case among 2000 infants. Had cost of Hib vaccine not been a major consideration, it would have been easy to mandate its use also under policy. But IAP does not feel justified in recommending the vaccine to all families, irrespective of their income. If the nutrition of an infant would suffer on account of using Hib vaccine, certainly it is against the infant's best interests to divert funds to Hib vaccine. We desperately need epidemio-logical data, but we are unable to collect them because we have not established the necessary infrastructure for conducting population-based epidemiological studies. For these reasons, Hib vaccine is optional (essentially based on affordability), but we hope that the ministries of health will take these issues more seriously in future. We also desperately need to get Hib vaccines at affordable prices. There need not by any apprehension that the antibody levels achieved with HB vaccine immunization starting at birth would be low. It is to overcome this potential deficiency that the third dose is recommended 4 to 6 months after the second; with such an interval the anti- body levels achieved would be very high and equal to any schedule avoiding the neonatal dose. T. Jacob John, |
