Immunization Dialogue Immunization in Cancer |
| There are a number of children with cancer who are long term survivors. It would be useful to get information regarding immunization policies that should be adopted in such patients: (i) during the course of chemotherapy, and (ii) after they have completed treatment. Particular emphasis needs to be laid on whether these children should be started on primary immunization or not once cancer treatment is completed. R.K. Marwaha, Reply The term cancer as applied to children includes leukemias, lymphomas and other solid tumors. Each one of these general categories includes different entities. Some of these conditions cause varying degrees of immunosuppression. Chemotherapy, radiation and corticosteroids which are given by way of treatment also result in some degree of immunosuppression. These considerations as well as the age of the children and the local epidemiology of infections that could be prevented by immunization are the factors to be taken into account in prescribing specific vaccines. In other words, generalizations are difficult and decisions must be taken on individual basis, in consultation with the other team-mates, particularly the oncologists. We can enunciate certain principles which will guide the choice of vaccines in individual cases. It is worth remembering that there are other conditions, such as immune function disorders of congenital nature, splenectomy for various reasons, corticosteroid treatment for diseases other than cancers, and increasingly commonly human immunodeficiency virus (HIV) infection, that cause immunosuppression. Immunosuppressive therapy is necessary in bone marrow transplantation (BMT), allogenic or autologous. In all these conditions a careful evaluation will be ne-cessary to choose vaccines and to choose the timing of immunization in relation to treatment, remission and the risk of infection according to various factors. Also we need to ask how the level of immune functions (or its suppressions) affects the need, the safety and the efficacy of each vaccine before it is considered for the child. In general all non replicating antigens are safe in children with immunosuppression although their efficacy may be reduced. Live antigens such as BCG, measles/MMR vaccine and oral polio vaccine (OPV) may cause adverse rections in certain situations, but not in others. Varicella zoster vaccine, although live, has a special place in immunization of children with cancer, as will be discussed later. In all children, the previous immunization with each vaccine must be reviewed. In general children with full primary immunization with OPV or measles vaccine are protected from disease in spite of mild to moderate immunosuppression. Incompletely immunized children need catch up doses. Some may need booster doses; other may need special vaccines such as varicella vaccine or pneumococcal vaccine. Illustrative examples are given below. Children with leukemia in remission may be given OPV, measles or MMR vaccine about 3 months after the last chemotherapy, provided it is necessary on account of lack of previous immunization or as reinforcing dose. A similar interval is recommended for giving varicella vaccine also. In acute lymphocytic leukemia in remission, there is one recommendation to check blood counts and ensure over 700 lymphocytes and 100,000 platelets/cu mm before giving the varicella vaccine. Some experts give pneumococcal vaccine to children older than 24 months, with Hodgkin's disease, and delay initiation of therapy for 10 days to 2 weeks. Such children, and those undergoing splenectomy, are at increased risk of invasive pneumococcal infection; that is the reason for this special recommendations. If the child is under 5 years old, Hib vaccine may also be beneficial since there is an increased risk for invasive Hib disease also. Children on steroids need special assessment. In general, children receiving low dose steroids can be give live virus vaccines without problem. Those given high dose steroids (2 mg or more/Kg or over 20 mg of prednisone or its equivalent) should not be given live vaccines while they are on steroid therapy. If the course has been short (2 weeks or less), vaccines may be given 2 weeks after discontinuing steroids. If the course has been longer, one month gap is recommended. Children with cancers come to hospital repeatedly and may be at increased risk of nosocomial hepatitis B virus infection. Therefore they may be given HB vaccine at the very beginning or at a convenient, early opportunity. Since there is no risk of adverse reaction, but there may be suboptimal immune response, one additional dose or adult patency vaccine in regular doses may be given. T. Jacob John, Thekkekara, 2/91, Kamalkshipuram, Vellore 632 002, India. |
Should a Sick Child be Immunized I would like to draw attention to the following situations: 1. It is recommended that even during diarrhea OPV drops should be administered, but, this dose should not be counted and then the OPV should be administered again when diarrhea is controlled. As it is known that OPV administered during an episode of diarrhea may not produce the optimum effect, so there is a need to repeat the dose. (i) Why should a child with diarrhea be taken to the Immunization Center causing inconvenience to the child and the mother, as the OPV dose administered will not be very effective?
(ii) Would the OPV administered duirng diarhea interfere with uptake of the subsequent OPV dose given a few days later? 2. What would be the effect if a 7-8 months old child who had fever of 2 days duration is administered OPV and subsequently develops Measles? 3. A child with exacerbation of asthma is on oral corticosteroids and is immunized. 4. An ill child administered any vaccine, later develops complication of the disease, the vaccine may be blamed for the complication or even death. Why should we not advise the parents to defer the immunization if a child is ill, unless we are certain that the present illness will not in any way interfere with the immunization process? My query is regarding immunization in general, with special reference to Pulse Polio Campaign. Yash Pual, |
| Reply It is very important that all of us understand the principles based on which guidelines and recommended schedules of immunization are prepared. The general rule of thumb is that minor illnesses are not contraindications for giving a dose of a vaccine. Therefore, mild diarrhea is not a contraindication, even for giving oral polio vaciine. Similarly, mild fever, mild upper respiratory tract illness, etc. are also not contraindications. However, it is extrememly important that all of us understand the basic principles, rather than enunciate rules to fit with every situation. I am reminded of the story about the Jewish Pharisee's approach to religious rules, in the ancient past. On Sabbath day no work should be done as it is the day of rest. Now, work has to be defined. Travelling is work, but walking a few steps is not travel. Now travel has to be defined. Going out of one's home to another place is travel, hence work. Now one has to define the limit of one's home, and the number of steps which will constitute travel and what constitutes the home. The place where one's bed is the home and the gate of the home is the limit; more than 40 steps is travel. Therefore, in an emergency one could pack up one's bed roll and carry it and go any where, since the home is where the bed is and you are never more than 40 steps away from it! We should not want rules in such great detail. In this spirit let me answer the specific issues raised as questions. Please note that the above vignette is only for illustration and not for offending religion. 1. OPV can be administered to a child with mild diarrhea. Since the effect may not be optimum, at the next opportunity, give another dose and do not count the earlier dose. The point is, when the child is available for a dose of OPV, give it in spite of mild diarrhea, for we do not know for sure that the child will be brought back for another dose of OPV later. So the child gets the benefit of at least the present dose, even if its effect is not as good as in a well child. If the child is available again, repeat the dose. All these guidelines are for giving the best possible protection to the child and not to be stingy about a dose of OPV that might not perhaps give the best result. Look at it another way. The child takes a dose of OPV, but develops mild diarrhea the same day. Will the child come to harm? No. should the dose be repeated? Ideally, yes. During pulse polio campaigns, keep the contraindications to the minimum, namely very sick children in hospitals. Even there, there is no harm in giving vaccine to all those who are recovering, have chronic illness, are on antimicrobials, etc. but, they can be immunized just before sending home rather than giving it in the ward itself, where the probability of wild poliovirus transmission is very low. If it is one's own child or a child that you are confident to immunize after recovery, there is no compulsion to give a dose now and repeat it later. If on the other hand the child is due for a dose and is from a distant area, why not give it, since the next visit is not guaranteed? 2. The second question is for parents. There is no reason for the mother to insist on a dose of OPV on the stipulated day if the child happens to be unwell; it can wait a few days until the child is recovered. Here, the parents should know the implication of their decision and that they are responsible for taking the child to get the missed dose. If they decided to come to the clinic, no harm in giving a dose either. If the parents postponed the visit on account of a mild illness, thus not adhering to the appointment given by the doctor, will the doctor get upset? I hope not. 3. The OPV given during diarrhea is not likely to interfere with the effect of a subsequent dose a few days later. If the first dose resulted in `take' of vaccine virus, the next dose is unnecessary.If the first dose did not `take', then it cannot interfere with the next dose any way. This applies to each type of vaccine virus, type 1, 2 and 3. Cross-interference between types is not an important problem, as we had shown earlier by experimental studies. 4. If a child developed measles within a few days of taking OPV, the measles is unlikely to be modified or worsened (why should it be?) and the only problem might be that the vaccine was ineffective. Sometimes an infection like with measles virus may inhibit another virus infection, but there is no direct proof for it; on the contrary there have been many documented instances of dual and even multiple virus infections simultaneously in children. Since the OPV infects the gut even in infants with maternal antibodies against polioviruses, one would expect that the vaccine was effective in spite of elevated interferon level or other factors in a measles virus infected child. 5. Very short course of corticosteroid therapy and aerosol inhalation of steroids are not contraindications for immunization even with live viral vaccines. It may be better to give the vaccine soon after discontinuing steroids. If a child was given high dose of steroids (over 2 mg/kg or more of prednisone or its equivalent per day) for two weeks or more, then immunization with live vaccines should be postponed until at least a month after discontinuing steroids. 6. Both the doctor and to a certain extent the parents must know what the vaccines can, and cannot, do. Indeed many of the so-called adverse reactions to some vaccines are confounded by the naturally occurring illnesses of children. In the past, when polioviruses were highly endemic (and children were not protected by giving adequate doses of OPV and sufficeint coverage had not been achieved in the community), injections of DPT induced provocation poliomyelitis in several children. This was particularly so in children with mild fever, in whom the paralysis set in within one or two days of the injection (sometimes called aggravation polio). Today, this is not a cause for worry since poliovirus circulation has been drastically curtailed. The lesson to remember is to evaluate any sick child before giving any intervention. A well child can be given the dose appropriate for the visit, but if the child is unwell, the doctor must assess the situation before immunizing. If postponement will not affect the completion of the required doses, there is no harm in delaying immunization, except in the case of an outbreak (such as measles or polio or even whooping cough). In summary, one must view immunization in two ways; one for individual protection by personal prophylaxis and two, for public health purpose of control or elimination of an infection. The purpose of pulse polio immunization is solely for public health (elimination of wild polioviruses, by which all will be benefited, irrespective of being personally protected or not). Those children who had not been fully immunized will get the extra opportunity for personal protection also, but that is of secondary concern only. When previously fully immunized children participate in pulse immunization, no harm can come to them even if they had some illness. T. Jacob John, |
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