Immunization and vaccination are the most important intertwine public health interventions. They are cost-effective strategies aimed at preventing or reducing both the morbidity and mortality associated with infectious diseases. They mostly improve the quality of life of children, pregnant women and travelers. Immunization is the process by which the body is immune or has the ability to resist infectious diseases through administered vaccines. The body’s own immune system is stimulated to protect or fortify itself against subsequent infections, diseases or agent called immunogen.The goals of immunizations are to protect everyone from vaccine preventable diseases. They help to sustained seamless quality health.
Vaccination is the administration of potent vaccine into the body. This improves the immune system to the point of developing protection against specific infectious diseases. It is an active form of immunization. In simple terms, vaccination is the scheduled administration of vaccines parenterally, orally or by spraying into the body. Immunization is the security the body enjoys by factor of protection induced by stimulated immune system upon administration of relevant vaccines. Specific vaccines are produced against target infectious diseases.
For the purpose of this public document, do excuse the use of immunization and vaccination interchangeably. Immunizations or vaccinations protect target populations from infectious diseases. Vaccines are introduced to trigger immune response which tricks the body to think that it is exposed to disease to fight naturally. Vaccines contain, in killed or highly weakened form, the same antigens or parts of the antigens that cause the diseases they fight. Immunity (body’s ability to defend itself against diseases caused by certain bacteria or viruses) may occur naturally (after exposure to the bacteria or viruses). Immunity can be conferred through vaccinations by expert health professionals.
Immunization lowers incidences of diseases and frequent visits to the hospitals by children and adults. It thereby maximizes the use of time and money. A deadly disease of public importance which causes paralysis and death among children is poliomyelitis. This is still found in developing parts of the world among people who have never had the poliovirus vaccination. Or who missed doses of the vaccine or travelers to areas where poliomyelitis is still prevalent.
Types of immunization
There are two types of immunization. They are:
Active immunization: This involves administering immunogen which can be live/attenuated, killed/inactivated, toxoid or subunit in origin. Active immunization occurs when a living body is exposed to an immunogen in a controlled way. That helps the body to learn to protect itself from further or future infections. Artificially acquired active immunity can be stimulated by a vaccine containing antigen. Active immunization stimulates the body’s natural defense mechanism. This is in response to a vaccine by producing substances such as antibodies and white blood cells. The antibodies and white blood cells recognize and attack the specific bacteria or virus inside the vaccine. So, any time someone is exposed to a specific bacteria or virus, the body efficiently and automatically produces antibodies and other substances. These antibodies prevent or lessen the attack of infections or diseases. Vaccine’s effectiveness depends on the immune system’s ability to replicate and elicit response that adequately mimics the natural infection.
Passive immunization: Here, the pre-formed immune system’s antibodies are administered directly into individuals who are recently exposed to infections. Vaccine-provided antibodies or lymphocytes made from animals or human donors can confer passive immunity. Passive immunization with serum or globulin (antibodies) from immune persons has been administered to protect people from viral infections. This type of immunization is good for people whose immune system does not respond sufficiently to an infection. Also it is good for people who acquire an infection before completing vaccination. Or people whose occupations easily expose them to infections.
Passive immunization occurs physiologically and lasts for few weeks within which the body gets rid of the injected antibodies. It can be used to transfer antibodies from pregnant mothers to their children. This protects the baby before and shortly after birth. Artificial passive immunization is passed through injection especially in cases of recent outbreak of a particular disease. Also, it is useful in emergency treatment of toxicity, as in tetanus infection.
Types of vaccines for immunization
There are four major types of vaccines. They include:
- Live-attenuated vaccines: Are against Measles, Mumps, Rubella (MMR), Rotavirus, Yellow fever, Smallpox, Varicella and Influenza. It is very important to note that for safety concerns, vaccines containing live organisms or viruses should be avoided. They should be delayed in AIDS patients, pregnancy or patients taking immunosuppressant.
- Inactivated vaccines: Contain live but weakened organisms or viruses. Examples are Bacilli Calmette Guerin (BCG) vaccine against Tuberculosis, Oral polio vaccine, Oral Cholera vaccine and Oral typhoid vaccine.
- Subunit, recombinant, polysaccharide or conjugate vaccines: Produced through recombinant Deoxyribonucleic acid technology. They include vaccines against Haemophilus influenzae type b (Hib) disease, Hepatitis B and Human papillomavirus. Others are Whooping cough (part of the DTP combined vaccine), Pneumococcal disease, Meningococcal disease and Shingles.
- Toxoid vaccines: Are altered form of toxins. They are produced from toxins, poisons or chemicals secreted by certain weakened or harmless bacteria or virus. The secretion from the harmless virus or bacteria elicits immune response. This is against the harmful effects of the toxin, infection or disease caused by bacteria or virus that produce the toxins. Examples are Whooping cough (Pertussis), Diphtheria and Tetanus vaccines.
Routes of vaccine administration
Vaccines and antibodies are normally administered:
- By injection into muscle (intramuscularly)
- By injection under the skin (subcutaneously)
- By injection into the vein (intravenously)
- Into the nose by spraying
- Orally as drops
Importance of immunization
People were immune to some infectious diseases after surviving their attacks. That was about the end of the fourteenth century before the inauguration of immunization, vaccination or inoculation. Immunity through immunization can be achieved without the consequence of ill-health and life-threatening complications. Once a person is immunized, specific immune cells called memory cells protect the individual from re-infection by same infection. Some vaccines provide lifelong immunity. Some require booster doses to maintain immunity.
Globally, more than two million deaths are delayed or prevented annually through vaccinations. Despite this fact, vaccine-preventable diseases remain the most common cause of about three million childhood morbidity/mortality annually. The primary benefits of immunizations are to reduce mortality and morbidity in adults and children. Also it promotes quality life, good health and survival amongst children and women especially.
Recently, there are improvements in accelerated routine and supplementary immunization activities especially in developing nations. Immunizations are often more comfortable and less risky. It is safest way for adults and children to gain immunity against specific vaccine preventable deadly diseases. In developed nations especially, some infections or diseases are almost completely eradicated. This is through relevant immunizations, courtesy of dedicated health care professionals and elite parents. These groups ensure that no routine vaccination schedule for targeted children and adults are missed.
Immunizations prevent families from getting infections that have no ready medical treatments. Immunization is the only enabling health factor by which the body defends itself better against certain bacteria or viruses. When people are fully immunized against a disease or infection, they are usually protected. Also, it helps to reduce attack of the disease or infection because no vaccine is 100% effective. Immunizations protect and prevent people from spreading serious diseases or infections. In communities and countries, immunizations have actively interrupted epidemics of major infectious diseases. Measles, mumps, whooping cough; and almost eradicated smallpox and poliomyelitis are interrupted.
According to the American Centers for Disease Control and Prevention, active immunization or vaccination is so important that the Center named it one of the “Ten Great Public Health Achievements of the 20th Century”.
It is therefore evident that immunization is a veritable tool for controlling and eliminating life-threatening infectious diseases. It is the most cost-effective health prevention. Also, it is a proven strategy for easy access of most hard-to-reach and vulnerable populations.
Paying close attention and observing strictly the immunization schedules and supplementary initiatives are very important. This helps to improve health and stop spread of diseases in families and global community. Available vaccines today are very effective, well tolerated with minor side effects.
Few people with impaired immune systems (like diabetes, HIV or cancer patients) may be susceptible to diseases. They may not benefit fully from vaccinations or may not develop immunity even after been vaccinated. Such individuals can enjoy protection against the epidemics of infectious diseases when people in their environment are fully vaccinated. Also, target and healthy populations not fully immunized are not better than the people whose immune systems are compromised. This group is at risk in terms of import and spread of vaccine preventable diseases in schools and densely populated areas.
Therefore, get vaccinated and stop the import and spread of vaccine preventable infections, locally and internationally. It simply means that if you are not timely and fully immunized with relevant vaccines, you are not protected. You are equally harmful to your neighbours, causing preventable huge and diverse costs to humanity. Immunization is very important for both children and adults. It reduces the rate of hospitalization, maintains immunity and promotes of healthy aging.
Vaccine preventable infections
Globally, immunizations can protect both children and adults from:
- Human papillomavirus (HPV)
- Measles (red measles)
- Rubella (German measles)
- Tetanus (lockjaw)
- Varicella (chickenpox)
- Pertussis (whooping cough)
- Pneumococcal infection
- Blood infection
- Ear infection
- Haemophilus influenzae type b
- Hepatitis A
- Hepatitis B
It is important to emphasize that appropriate immunizations with potent vaccines are easier and less risky. They help the immune system to respond and build sustained immunity against the above severe infections and health challenges. Visit standard health facilities for expert advice and monitoring of your health and vaccination status. It is absolutely necessary to take charge and partner in your good health protection and promotion through recommended vaccinations.
Certain vaccines are given only once. Others require support or booster doses. The doses help to maintain adequate immunity and sustained protection against vaccine preventable diseases in children and adults. Generally, the schedule of recommended routine immunizations can differ based on location. Also the schedules depend on child’s health status, types and availability of vaccines. Some vaccines are combined mainly for convenience. These routine immunization schedules whose delivery should be tracked or recorded with health programme cards include:
- At birth: Hepatitis B vaccine is normally administered within 24 hours of birth. Also it should be given at any age or at 1 month of birth particularly for low weight infants. The second dose should be given 1 to 2 months after the first dose.
- At two months: The first doses of the following vaccines are administered. They are Diphtheria, Pertussis and Tetanus (DPT) vaccines and Haemophilus influenzae b (Hib) vaccine. Others are Oral inactivated Poliovirus (OP) vaccine, Pneumococcal conjugate (PC) vaccine and Rotavirus vaccine.
- At four months: The second doses of the following vaccines are administered. They include Diphtheria, Pertussis and Tetanus (DPT) vaccines and Haemophilus influenzae b (Hib) vaccine. Oral inactivated Poliovirus (OP) vaccine, Pneumococcal conjugate (PC) vaccine and Rotavirus vaccine are included.
- At six months: The third doses of the following vaccines recommended. They are Diphtheria, Pertussis and Tetanus (DPT) vaccines, Haemophilus influenzae b (Hib) vaccine, Pneumococcal conjugate (PC) vaccine and Rotavirus vaccine.
- At above six months and annually: Influenza (Flu) vaccine is recommended.
- At six to eighteen months: The doses of the following vaccines are administered. They are Oral inactivated poliovirus (OP) vaccine and Hepatitis B vaccine.
- At twelve to fifteen months: Haemophilus influenzae b (Hib) vaccine and Pneumococcal conjugate (PC) vaccine are recommended. Also Chickenpox (Varicella) vaccine and combined Measles, Mumps and Rubella (German measles or MMR) vaccines are recommended.
- At twelve to twenty-three months: Hepatitis A vaccine is given at interval of at least 6 months.
- At fifteen to eighteen months: Combined Diphtheria, Pertussis and Tetanus (DPT) vaccine is recommended.
- At four to six years: Combined Diphtheria, Pertussis and Tetanus (DPT) vaccine and Oral inactivated Poliovirus vaccine (OPv) are recommended. Also, Chickenpox (Varicella) vaccine and combined Measles, Mumps and Rubella (German measles or MMR) vaccine are recommended.
- At eleven to twelve years: Human papillomavirus vaccine, combined Diphtheria, Pertussis and Tetanus (DPT) booster (also recommended during each pregnancy) and Meningococcal conjugate vaccines are given.
- At sixteen to eighteen years: Meningococcal B vaccine may be given.
- At special circumstances, particularly for travelers and during outbreaks: Hepatitis A vaccine and combined Measles, Mumps and Rubella (German measles or MMR) vaccine are given. Oral inactivated Poliovirus vaccine (OPv), Pneumococcal conjugate (PC) vaccine, Meningococcal B vaccine and Influenza (Flu) vaccine are recommended.
Though improved sanitation, hygiene and other living conditions have generally promoted healthier environment. Also there is reduction in risks that favour exposure to vaccine preventable diseases especially in disease endemic regions. Irrespective of the above, recommended childhood immunizations and booster vaccines are still very important for sustainable quality life.
Efficacy of vaccines and possible side effects of immunization
Most of the recommended childhood and adult immunizations are 90%-100% effective against vaccine preventable infections. However, for reasons that are not fully understood, occasionally a child will not have total immunity after vaccination. This is the more reason to get children fully vaccinated. Some children, in whom the vaccine is 100% effective, protect the few who have not been completely immunized. This gives everyone’s reduced or no chance of exposure to preventable infections.
The only reason for vaccination restriction is in case of a serious, life-threatening allergy. Anaphylactic reaction or shock which results to facial swelling, difficulty in breathing or dizziness could restrict vaccination. This restriction is critical in poorly equipped health facilities where the above allergies are difficult to be managed immediately.
Today, there are best practices in vaccine production and use of modern equipment. Based on that, myths and misinformation about vaccine safety and immunizations are regarded as old fables. The fables are against quality life. And derogatory marks of underdevelopment, illiteracy and ignorance. Truly, potent and proven vaccines are drugs which may cause side effects. The good thing is that their minor side effects are insignificant compared to the infectious diseases they prevent.
The side effects mostly experienced include redness and localized swelling in the site of the injection. Soreness and low-grade fever or body hotness are common. Minor irritation and vomiting are rare. Usually the side effects are easily, readily and appropriately handled by health care professionals. Moreover, the side effects are not harmful and they usually disappear within few days. Adults who express nervousness or fear of injections should take calming breaths or cough as the needle goes into the body within a second. In case of any unusual health problem after vaccination, care providers and the public should keep or issue reports on Vaccine Adverse Event (VAE). The report should be sent to the designated disease control centres for relevant documentation and interventions.
Immunizations or vaccinations which have good objectives suffer recurrent setbacks especially in developing economies. Some of the factors militating against full immunizations coverage include:
- Ethnicity, misconception or misinformation and religious beliefs or myths.
- Inadequate vaccines and investment in personnel, facilities and support drugs. Poor management of existing resources.
- Lack of relevant technologies, basic health infrastructure and tools.
- Lack of sufficient political will in favour of implementing sustainable immunization policies, plans and strategies.
- Lack of adequate and sustained public education/awareness creation. Poor community engagement through targeted advocacy on immunization programmes.
- Unreliable monitoring of the performance indicators through quality on-going epidemiological surveillance. Unreliable laboratory confirmation and impact assessments of the target population (children and women).
- Internal conflicts or wars, adverse weather conditions and hard-to-reach/border communities.
High immunizations coverage is good health output. It has ultimate outcome of decimating or eradicating the incidences of morbidity and mortality from vaccine preventable infections. Also, high coverage measures level of protection and break in the transmission or spread of infections locally or globally. The way forward in achieving high and sustained immunizations coverage hinges on conscious and strategic efforts of all stakeholders in tackling the above challenges.