Immunization is a scientific means of making people particularly children resistant to deadly or killer diseases by activating their own immune system (the body’s defence to diseases). Scientists have succeeded in getting vaccines or chemical substance which can be injected into a person or given orally to act as protection against diseases.
Vaccines aim to prime the immune system to the antigens of a particular microbe so that a first infection induces a secondary response. “Never in the history of human progress” wrote the pathologist Geoffrey Edsall, “has a better and cheaper method of preventing illness been developed than immunization at its best”. It is a sobering thought that the greatest success story in medicine, the elimination of smallpox, began before either immunology ( the study of our body’s defensive mechanism) or microbiology ( the study of tiny organisms that cannot be seen with our naked eyes) where recognised as disciplines- indeed before the existence of microbes or the immune system was even suspected. This was as a result of the pioneering work of Jenner with Vaccinia cell forms and now referred to as “vaccination”.
The English physician Edward Jenner is regarded as the founder of modern vaccination but was by no means the first to try the technique. The ancient practice of “variolation” dates back to the 10th century China, and arrived in Europe in the 18th century by way of Turkey. The technique involved the inoculation of children with dried material from healed scabs of mild smallpox cases, and was a striking foretaste of the principle of modern viral vaccines. This practice was, however both inconsistent and precarious, and Jenner’s innovation was to show that a much safer and more reliable protection could be obtained by deliberate inoculation with cowpox (vaccinia) virus. Milkmaids exposed to this infection were traditionally known to be resistant to smallpox and so retained there smooth complexion. In 1796, Jenner tested his theory by inoculating 8-year old James Phipps with liquid from a cowpox pustule on the hand of Sarah Nelmes. Subsequent inoculation of the boy with smallpox produced no disease.
He ultimately achieved world fame. His house in Berkeley is now preserved as a museum and is used for small symposia by the British society of immunology.
Vaccination and related biologic products constitute an important group of agents that bridge the disciplines of microbiology, infectious diseases, immunology, and immunopharmacology (study of drugs used to boost our defence to diseases). While a complete discussion of these agents is beyond the scope of this work, it will be, however, of great good if we start by looking briefly at the concept of immunization, which I believe will help to widen our understanding of its significance to a healthy living. Immunization can be classified as passive or active:
Active immunization consists of the administration of antigen (any substance considered foreign by the body’s defence) to the host to induce formation of antibodies (proteins produced in the body against an antigen) and cell mediated immunity. This form of immunization is practiced to induce protection against infectious agents and may utilize either inactivated (killed) material or live attenuated agents.
Passive immunization on the other hand consists of transfer of immunity to a host using preformed immunologic products. Passive immunization is useful for; individuals unable to form antibodies, prevention of diseases when time does not permit active immunization e.g. after an exposure to the infection, for treatment of certain diseases normally prevented by immunization (e.g. tetanus), and for treatment of conditions for which active immunization is unavailable or impractical (e.g. snakebite). However, active immunization is generally preferred to passive immunization because higher antibody levels are sustained for longer periods of time requiring less frequent immunization, and in most cases because of the development of concurrent cell mediated immunity.
The aims of vaccination vary from blocking transmission and preventing symptoms to eradication of the disease. However, the most ambitious aim of vaccination is eradication of the diseases. This has been achieved to a greater degree for smallpox. The smallpox vaccine, vaccinia, was in many ways the ideal vaccine. Smallpox vaccination worked best because the vaccinia virus, a natural animal virus, shared antigens with the smallpox virus.
The remarkable decline in poliomyelitis, the leading cause of paralysis in young children in West Africa and Sierra Leone in particular, is due to the use of one or other of the two vaccines;
the killed virus (Salk 1954)
the live attenuated virus (Sabin 1957)
Both these vaccines are effective. For oral polio vaccines (OPV), this is the one mostly used in Sierra Leone, attenuation of this vaccine was by passing through monkey kidney cells or human embryo fibroblast. Analogous methods have been used for measles, rubella, mumps, and yellow fever, all of which are viral infection.
The Bacille Calmete Gue‘rin (BCG) is the one well established bacteria vaccine. It is given mainly to prevent tuberculosis (TB), one of the 10 leading causes of death in the world. It is given to approximately 90% of the world’s babies at birth and has been shown to protect against the most severe form of tuberculosis, such as TB meningitis (inflammation of the inner coverings of the brain) apart from its tremendous role in preventing TB of the lungs. A more recent development however is the production of an attenuated strain of salmonella typhi (the bacteria that causes typhoid fever), produced by exposure to chemical mutagens, which has been proven to be better than the old killed typhoid vaccine. What could this mean to Sierra Leonean? At present, 98 percent of hospital presentations with fever, diarrhoea, malaise, anorexia and the like are being diagnosed as typhoid fever. Many of these, on proper examination, are not. What can we say to account for the thousand of lives which are being endangered with ciprofloxacin (the drug of choice for typhoid fever in Sierra Leone)? Where does the fault lie? Is it that the technicians are not well trained or that the laboratories are not well equipped? Well, this will definitely end in the noble hands of our government officials who have been doing so well in upgrading the health sector in Sierra Leone in the very resent past. There involvement however might take time; therefore, may I humbly suggest that we embrace vaccination as a means of preventing countless number of diseases.
Well, with such brief knowledge of immunization, could we now sit by as parents and allow our children to run into such terrible disease just to rush with them to health centres, or for the government and other health officials to spend time and money in radios and public gathering encouraging us to vaccinate our own blood borne off- springs? The answer, I believe, is no. However, this work will be half way through if I fail to outline the relevance of vaccination to our society.
About 13years ago, a lot of infants who where not vaccinated or immunized died and many more left disabled as a result of attacks of diseases like poliomyelitis, whooping cough, measles, diphtheria, chicken pox and even small pox. A good number of children who survived these diseases where those whose parents had the opportunity of taken them abroad for treatment or going to abroad near the term of delivery so as to immunize them as soon as they were born. Today, however, the government in partnership with other health organization offers free immunization for polio, TB, tetanus and other diseases as soon a child is born and many more as he grows. When free polio and other immunization programmes began about a decade ago, many parents reluctantly could not take their children for it. A good number of children who survived the diseases where those whose parents took the nice decision to have their children inoculated. Most parents who did all they could to thwart the altmistic efforts of the health officials, who pleaded with them to bring their children for inoculation lived to regret their actions. While children who were inoculated lived, their own children died in their dozen.
Therefore, it goes without saying that immunizations save all parents from loosing their children prematurely to deadly but preventable diseases. Immunization has begun an era where parents can have children and boast that barring accident and other ways of losing them are minimized, their young ones will grow up into useful adults. Children who are timely and properly immunized can enjoy good health in their infant years. This will save the money that should have been spent on medication for addressing other family needs. Indeed, there is a need to find ways of sparing the little money we earn as the global economic trend is presently in disarray. The convenience which immunization enables parents to enjoy is almost incalculable.
Vaccinated children definitely grow up to be good, healthy and responsible adults. Their growth is not impaired or stunted by measles, poliomyelitis or any of those debilitating diseases. Some of these diseases have the ability of invading the central nervous system(brain and spinal cord), leading to several neurologic presentations; which may end up into severe mental retardation.
Age is an inevitable limiting factor affecting the work force, meaning that each year; students must graduate from tertiary institution to solidly replenish old, retiring men and women from all fields. These must be people of high intelligence quotient (IQ), otherwise the country will go down the drains – a country with the first standard and internationally recognised university in the sub region. This might be a leading reason why we almost always need people from overseas to look into our local matters while we still train professionals.
Immunization, for emphasy, has both direct and indirect benefits. The direct effect protects those successfully immunized and, by reducing the incidence of infection, results in fewer infected individuals to transmit infection to those still susceptible. The later therefore benefit indirectly from those who have been immunized. In general successful vaccination of the majority of the population increases the age at which infection occurs. Typically, the risks from infections and vaccinations change as vaccination coverage increases. When infection is common and vaccination rare, the risks due to the former are invariably greater, often by many orders of magnitude. When infection is very rare as a result of vaccination, the reverse may be true. Paradoxically, the risk of vaccination will always be lesser once vaccination has eliminated infection.
Different vaccination coverage is needed to eradicate different infection. Other things being equal, the higher the reproductive rate of an infection (the larger the value of Ro- i.e. the larger the number of people subsequently infected by one infected individual) the harder it will be to eradicate an infection by mass vaccination. Example, the global eradication of measles with its Ro of 15-17 will certainly be more difficult than the eradication of smallpox with Ro of 2-4. By the way, smallpox has almost been eradicated globally. Polio is the next disease that may be eradicated-Europe was declared polio free in 2002, and the Global Polio Eradication Initiative aimed at certifying the world polio free by the end of 2005. In 2000 polio infections occurred in only 20 countries, Sierra Leone being one of them, with fewer than 3000 cases diagnose worldwide. So it is clear we have a role to play in helping international donor to stop wasting money on these deadly but preventable diseases.
Finally, in the search for new vaccines, we must not lose sight of the fact that some diseases can be controlled equally well by other means. In the developed world, public health measures rather than vaccines (antibiotic) eliminated malaria and cholera, which still account for the greatest morbidity in Sierra Leone, and reduce the incidence of TB. It could be argued that tropical diseases such as schistosomiasis (bilharziasis) could also be controlled by reducing contact with snails or infected ponds, rivers or streams. However, vector control is not easy in practice and, like chemotherapy but unlike vaccination, needs to be maintained more or less indefinitely.
With this, it is clear from all quarters that co-operation with the ministry of health and other health organisations in their immunization programmes, which they have been emphasizing on, will tremendously save us from spending huge sums of money on herbalist, sacrifices and fruitless hunting for so called witches and wizards that allegedly behind all infant deaths in the nation.
© Copyright by Awareness Times
Newspaper in Freetown, Sierra Leone.