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Sunday, November 10, 2013

The Importance of Immunisation and the Consequences of Shunning it (Hepatitis B Infection)

Nigeria joins the rest of the world to celebrate World Immunisation Day today. In this interview with MOTUNRAYO JOEL, a Senior Registrar and Chief Resident, Department of Community Health, Obafemi Awolowo University Teaching Hospital Complex, Ile-Ife, and member of the West African College of Physicians, Dr. Olujide Arije, speaks about the importance of immunisation and the consequences of shunning it
When is the ideal time for mothers to immunise their babies?
Routine immunisation is done in a schedule that consists of several vaccines for preventing occurrence of several diseases. The Ministry of Health, under its immunisation programme, has given the schedule for immunisation in Nigeria. The first set of vaccines, which should be given at birth, consists of Bacillus Calmette-Guerin vaccine for preventing tuberculosis, the first dose of oral polio vaccine  for preventing poliomyelitis and the first dose of Hepatitis B for preventing hepatitis B infection. The next set consists of the first dose of DPT vaccine for preventing diphtheria, pertusis and tetanus as well as the second doses of OPV and HBV. This should be given in the sixth week from birth. The next set, given in the 10th week, consists of the second dose of DPT as well as the third dose of OPV. The next set, given in the 14th week, consists of the third doses of DPT and HBV as well as the fourth dose of OPV. Measles and yellow fever vaccine are to be given at nine months. Though not a vaccine, Vitamin A is administered alongside in the immunisation schedule in the sixth month and the 12th month. Recently, the pentavalent vaccine was introduced in a number of states in Nigeria by the Ministry of Health. It combines the HBV vaccine, the DPT vaccine and newly introduced vaccine, Hemophilus Influenze B vaccine, into one combination so that the child will only need to be pricked by the needle once for them. It has however not changed the timing on the immunisation schedule.
In direct response to the question therefore, the recommended time to have babies immunised are: at birth, six weeks, 10 weeks, 14 weeks and nine months. This makes at least five contacts for a child before the age of one.
What is the difference between natural immunity and vaccine-induced immunity?
Natural immunity is either the immunity transmitted from a mother to her child during pregnancy or that acquired following recovery from infection. For instance, maternal antibodies from the mother can protect the child from measles for up to nine months following which the child must be immunised against measles. A child that is not immunised can become infected with the measles virus. If such a child survives the measles infection, he/she will become permanently immune specifically to measles infection. It should be noted that it is not all infections that have this natural history of conferring life-long immunity following infection. Vaccine induced immunity is immunity acquired by deliberating introducing materials (vaccines) into the body to induce the presence of antibodies that can fight against diseases. There are basically two types. In the passive type, preformed antibodies are introduced into the body. These however confer immunity for a relatively short period. The second type is active immunity where the body is stimulated to form its own antibodies against specific infections.
What diseases should a baby be immunised against?
The diseases for which vaccination is given in the national immunisation schedule are tuberculosis, poliomyelitis, diphtheria, pertusis, tetanus, hepatitis B infection, hemophilus influenza infection, measles and yellow fever. There are some other vaccines available but these are not included in the national schedule for immunisation and can be procured privately.
What risk can a child not immunised face?                       
Every child that is born acquires some protection from the mother by the passage of some immunity from the mother to the child during pregnancy. Of course, it is a mother whose immunity is competent that can pass on immunity to the child. The protection acquired by the baby is temporary and soon wears out. Maternal antibodies transmitted to the infant are gradually lost over a period of six months. At this time, if the baby does not acquire immunity by some other means then he/she will be at risk of acquiring the diseases which the mother’s immunity protected him/her from before. It is based on the lifespan of the immunity acquired from the mother that the immunisation schedule has been created. Furthermore, there are some disease conditions for which immunity is not passed from the mother to the child. For instance, BCG is given at birth to offer protection against tuberculosis because the mother does not pass immunity against tuberculosis to the child. Whereas, measles vaccine is given at nine months because the child is still protected from measles for up to nine months by the immunity acquired from his/her mother. Children are at risk of developing these vaccine preventable diseases listed if they are not immunised against them.
Are there vaccines adults should take for protection against diseases and what are the diseases?
Pregnant women are given the tetanus toxoid during their pregnancy. The primary aim is to enable them pass on some immunity against tetanus infection to the new born children. If they receive five doses in all as recommended, then they will be protected for life.  Also, some professions are more exposed to the risk of certain infections than the general population. For instance, health workers are at higher risk of acquiring hepatitis B infection due to exposure to blood and other body fluids. Thus, these workers are advised to receive the complete dosage of the HBV vaccine. Furthermore, while some vaccines can confer life-long immunity, for example, measles, others can only provide protection for a number of years thus the need for booster doses. Yellow fever vaccine should be repeated 10 years after the last dose. Moreover, some countries require that visitors be vaccinated against yellow fever with the evidence of a current yellow card. The Human Papilloma Virus vaccine is administered to women to protect against the HPV infection that leads to cervical cancer. Cerebrospinal meningitis vaccine is usually given to high risk groups or during outbreaks of the disease.
There are claims that some vaccines are safer than others?
The safety of vaccines is one that must be taken seriously just like the safety of any other pharmaceutical product. There are stages that each drug/vaccine must go through before regulatory agencies can allow their usage in general population. Once drugs/vaccines pass these stages, they are safe for use until otherwise proven. However, like other drugs, vaccines can cause anaphylactic reaction in some individuals particularly if such individuals are allergic to one or more of the components used to formulate the drug/vaccine. In that case, such individuals are advised not to receive that particular vaccine again. Another possibility is the occurrence of vaccine-induced disease where the vaccine causes the disease it was administered to prevent. The reason for this is some vaccines are created from the actual disease causing agent which has been attenuated. The meaning is that the disease causing agent is manipulated so that it does not cause frank disease yet it causes the body to react in creating antibodies; if an actual disease causing agent enters the body, there will then be antibodies ready to fight it. In very few cases, this attenuation may fail and result in vaccine-induced infection.
What are the dangers of combining vaccines?
One of the practices we have in our health facilities when we have children that have missed their recommended vaccination is to administer all that has been missed up to that time. We just ensure we do not administer two vaccines into the same site. Furthermore, the dangers in multiple vaccinations are reduced by using such vaccine combinations as the pentavalent vaccine that contains vaccines against diphtheria, pertusis, tetanus, Hepatitis B and Hemophilus Influenza B in a combination. This is safe and very effective.
What is your take on myths that vaccination harms children?
People have the right to know what is being given to them or their children,  therefore there is a need to dispel all myths about vaccination in a culturally sensitive manner. There are reports all over the Internet about the safety of vaccines, some of these bordering on conspiracy theories. As health workers, we must dispel these myths. However it is not enough to just talk about them, as a country we must get our own experts and other independent agencies to do quality control and carry out laboratory tests on any vaccine in question to ensure that all the myths are dispelled in a proper and scientific manner.
Is there enough awareness about immunisation?
There is a lot of awareness that is ongoing concerning immunisation. For instance, in each local government area in Nigeria, there are dedicated members of staff whose job is to administer and manage vaccination related activities. Same thing applies in each Ministry of Health in the state and the Federal Ministry of Health. These workers are actively supported by local and international partners, donors and collaborators. The local, international and global cooperation is what has made vaccination services free to end users. This fact will be appreciated when one knows how much pharmaceutical companies charge for their vaccines.  Though there are important issues about awareness, but what cannot be guaranteed is whether merely being aware will create a behavioural change towards acceptance of vaccination. For instance, in many places where vaccination was resisted, it wasn’t that they were not aware of it, rather they were suspicions about the motives behind vaccination and the safety of the vaccines. Hopefully, we have moved far from this point now. Other factors militating against taking immunisation include illiteracy especially of the mothers and hard- to-reach areas.
What can government do to strengthen awareness on immunisation?
The present awareness campaign by government at all levels must be sustained, even improved upon. Furthermore, vaccination and the need for it should be introduced into school curricular so that future generations can imbibe it. This is a longer term plan though. Perhaps, there will be better acceptance of vaccines if they are manufactured in Nigeria. We must make progress in the direction of being self- sufficient in the production of vaccines. Childhood mortality has decreased drastically even though it has not reached the levels in the more developed countries. The reason for this drastic decrease among other things is immunisation. Thus, there are both historical and scientific evidences that show that childhood survivability increased with the immunisation era.

By Joel Motunrayo

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