PAN recommends complete vaccination of every child born in Nigeria and those immigrating into Nigeria. The vaccine schedules are recommended by experts in PAN, in collaboration with others in UNICEF and the WHO.

PAN RECOMMENDED IMMUNISATION SCHEDULE

CATCH-UP VACCINATION FOR CHILDREN AGED BELOW FIVE YEARS

 CATCH UP VACCINATION SCHEDULE FOR CHILDREN AGED 5-18 YEARS WHO HAVE NEVER BEEN VACCINATED

VACCINE FOR SPECIAL GROUPS

Smallpox was a most feared disease resulting in 20-30% mortality and the disease left survivors scarred for life. As part of efforts to control the disease, inoculation, a practice of injecting some of the pox materials into healthy individuals was practiced as early as 10^th century AD. This practice met with varying success with some getting protected and others contracting the disease and dying. Following observations that milkmaids who caught the cowpox were protected against smallpox, Edward Jenner performed an experiment on James Phipps, inoculating him with cowpox material and then challenging him with smallpox. James Phipps was protected and Edward Jenner was the first to publish his works on vaccination as the practice came to be known in 1796. A hundred years later, Louis Pasteur made the first Rabies vaccine

To understand how vaccines work we must examine the immune system. Immunity is the ability of the body to recognize and tolerate what is “self” while getting rid of what is “non-self”. The body is equipped with the capacity to resist invasion by materials foreign to the body which are recognized as non-self. Following a first time exposure to foreign materials (antigens) which include microorganisms the cells of the immune system respond by developing antibodies, specific helper, and effector T lymphocytes (including cytokine-producing cells) and killer T cells which will help to get rid of the antigen. This reaction takes time and the organism would have caused disease before the immune system can eventually get rid of the organism.  A few of these immune cells develop a state of immunological memory such that when a similar organism is encountered again they respond with faster production of antibodies that bind with greater avidity and cells that kill faster thus getting rid of the organism before it can cause disease.

A Vaccine is any preparation which when administered is able to stimulate the immune system to produce specific responses that inactivate, destroy, or suppress a given pathogen (microorganism). Thus vaccination is the administration of a vaccine for the prevention of disease while Immunisation is the process of inducing immunity artificially. The two words are used interchangeably because vaccination leads to immunisation. Vaccination uses the concept of immunity by introducing materials that will induce immune response without causing disease and when an individual subsequently encounters the organism, he/she is able to mount an effective immune response to get rid of the organism without suffering the disease.

Content of vaccines and their mechanisms of action

Active immunisation is that which induces in the recipient a degree of immunity similar to that achieved from the natural infection and is able to prevent clinical disease. It involves stimulating the immune system to produce antibodies or cell-mediated immunity against an infectious agent. The immunity is produced by the individual’s immune system and is usually long-lasting.

Passive immunisation is the administration of exogenously (outside the body of the recipient) preformed antibodies. The immunity produced by this type of immunisation is temporary.

Although vaccination should lead to immunisation, this is not always the case. The determinants of immune response include

• Chemical and physical state of the vaccine
• Route/site of administration
• Vaccine dose
• Immunogenicity of the vaccine
• Host factors- age, sex, nutrition, presence of pre-existing antibodies, genetics, immune status, pregnancy

This is the resistance of a group to invasion and spread of an infectious agent due to the immunity of a large proportion of the group. To achieve this, high immunisation coverage is necessary. When there is herd immunity, the unimmunized in the population are protected because the infection is unable to spread as most people are immune. However when the proportion of those immunized is low then an infection can spread readily. Often a target of 80% immunisation coverage can achieve herd immunity but for highly infectious agents, herd immunity may require immunisation coverage of up to 90-95%.

All information on immunisation is evidence-based and is reviewed intermittently by the PAN sub-committee on immunisation to ensure that they are scientific, accurate, and based on recommendations by WHO, UNICEF, and the NPI.

Vaccination is one of the most cost-effective interventions in public health.  Smallpox a disease that ravaged and decimated populations was eradicated in 1977 by the use of vaccination. Poliomyelitis a disease which resulted in deaths and caused profound disabilities for millions of children was endemic in 125 countries prior to the global eradication initiative in 1988. There are currently only two endemic countries Afghanistan and Pakistan while Nigeria and indeed Africa was declared polio-free on August 25^th 2020 having not recorded any case of wild polio in the preceding 3 years.

At the regional level, the Americas have eliminated congenital rubella. Measles had been eliminated in many developed countries until the recent outbreaks stemming from vaccine hesitancy in their populations. Invasive Haemophilus influenzae type b infections were reduced by 99% following the introduction of a vaccine against the organism in the United States of America.  Vaccines continue to prevent 2-3 million deaths yearly. Vaccines work!

Benefits of immunisation

• Immunisation is able to prevent 2-3 million deaths globally each year.
• Immunisations prevent disease
• Vaccines prevent epidemics, and are also used to stop the spread of an on-going epidemic
• Disability is the hallmark of some diseases such as poliomyelitis. These disabilities are prevented by immunizing children.
• Vaccines help to save scarce economic resources. For example, billions of dollars used in the Smallpox eradication effort are now being saved because the vaccine is no longer being produced and quarantine facilities for Smallpox are no longer necessary.
• Vaccines avert suffering that may result from vaccine-preventable diseases.
• Immunisation helps to keep children healthy. When children suffer from vaccine-preventable diseases, their health and immunity are compromised. Immunisation keeps children healthy so that they are able to grow and develop normally. Healthy children become healthy adults and produce a healthy nation.
• When children are healthy, they are able to benefit maximally from their education
• Antibiotic resistance is a major global challenge. Vaccines can reduce the development of antibiotic resistance by preventing the occurrence of the infection in the first instance thus precluding the need for antibiotics.  When antibiotics are not used resistance does not occur.
• Immunisations contribute to sustainable development by enhancing productivity. Lost man-hours from parents having to look after children suffering from vaccine-preventable diseases are prevented. Economic losses from caring for children suffering from vaccine-preventable diseases or their long term effects are also prevented.

PAN collaborates with associations in conducting research and other programmes where sponsorship is offered. The study designs, data collection, fieldwork, analyses, interpretations are not influenced by donors. This website is sponsored and sustained by the dues of members of PAN and its contents are reviewed by the Immunization sub-committee regularly.

Vaccines are safe and effective if used correctly. However, no vaccine is completely without risk and adverse events can occasionally result after an immunisation. Adverse Event Following Immunisation (AEFI) is any medical occurrence which followed immunisation and which does not necessarily have a causal relationship with the usage of the vaccine. These events may be any unfavourable or unintended sign, abnormal laboratory finding, symptom or disease.  Such events may present as local reactions (redness, pain or swelling at the injection site), fever, irritability, convulsions, anaphylactic shock, adenopathy and encephalopathy.

Most vaccines will cause no or minor, non-serious adverse events. Serious events are extremely rare and generally do not result in death or long-term disability. These events are often not as deadly as the complications caused by the disease the vaccine is meant to prevent.

Categorization: AEFI can be categorized into two broad categories based specifically on cause, seriousness and frequency:

1. Cause-specific categorization
2. Vaccine reactions by seriousness and frequency

Cause – Specific Categorization: WHO has classified AEFI into five groups:

1. Vaccine product-related reaction – reaction to one or more of the inherent properties of the vaccine itself e.g. limb swelling following DPT (components of Pentavalent vaccine)
2. Vaccine quality – defect reaction – due to defect in the quality of the vaccine

3. Immunisation error related reaction – due to inappropriate vaccine handling, prescription or administration. It is largely preventable.
4. Immunisation anxiety-related reaction – due to anxiety about the immunisation e.g. fainting during immunisation.

1. Coincidental event – caused by things other than vaccine product, immunisation error or anxiety e.g. developing fever due to malaria shortly after immunisation.

Vaccines are safe and effective if used correctly. However, no vaccine is completely without risk and adverse events can occasionally result after an immunisation. Adverse Event Following Immunisation (AEFI) is any medical occurrence which followed immunisation and which does not necessarily have a causal relationship with the usage of the vaccine. These events may be any unfavourable or unintended sign, abnormal laboratory finding, symptom or disease.  Such events may present as local reactions (redness, pain or swelling at the injection site), fever, irritability, convulsions, anaphylactic shock, adenopathy and encephalopathy.

Most vaccines will cause no or minor, non-serious adverse events. Serious events are extremely rare and generally do not result in death or long-term disability. These events are often not as deadly as the complications caused by the disease the vaccine is meant to prevent.

Categorization: AEFI can be categorized into two broad categories based specifically on cause, seriousness and frequency:

1. Cause-specific categorization
2. Vaccine reactions by seriousness and frequency

Cause – Specific Categorization: WHO has classified AEFI into five groups:

1. Vaccine product-related reaction – reaction to one or more of the inherent properties of the vaccine itself e.g. limb swelling following DPT (components of Pentavalent vaccine)
2. Vaccine quality – defect reaction – due to defect in the quality of the vaccine

3. Immunisation error related reaction – due to inappropriate vaccine handling, prescription or administration. It is largely preventable.
4. Immunisation anxiety-related reaction – due to anxiety about the immunisation e.g. fainting during immunisation.

1. Coincidental event – caused by things other than vaccine product, immunisation error or anxiety e.g. developing fever due to malaria shortly after immunisation.

1. Mild – reactions that are easily tolerated by recipient, causing minimal discomfort and not interfering with daily activities
2. Moderate – reactions that are sufficiently discomforting and interfere with daily activities.
3. Severe – reactions that prevent normal daily activities e.g reaction that prevent school attendance in a young child or that causing parents to seek medical attention.

PAN’s policy on immunisation is based on scientific and epidemiologic data in partnership with Government and Non-Government organisations that promote child health and this is updated regularly. PAN is actively involved in immunisation activities in Nigeria. As the chief advocate for Nigerian children, the recommended schedule by PAN has been successfully used in advocating for the addition of new vaccines to the national immunisation schedule; It should be noted that the schedule presented here is more encompassing than the schedule operated by country and represents what PAN considers should be optimal immunisation for the Nigerian child and any child within Nigeria’s borders.

Vaccines are made from a variety of similar ingredients, although they differ in individual constituents. They may also contain residual by-products from the production process. Knowing the precise content of each vaccine can be helpful when investigating adverse events following vaccination and for choosing alternative products for persons with allergies to certain components.

Active components: This consists of the antigen; which is a form of the virus, bacteria, parts of the virus or bacteria or toxin causing disease. The antigen is however modified in some vaccines for example oral polio, the organism can replicate and mimic a natural infection but it is weakened so it is not able to cause disease;  in others, it  can no longer replicate because it is killed and cannot  cause disease but it can elicit an immune response ( which is what is needed). The content of newer vaccines may be the genetic code that produces the antigen to which the body responds and this confers immunity or an innocuous virus that contains the code for producing the antigen which the body responds to.

Adjuvants: Adjuvants are a highly heterogeneous group of compounds that have the ability to enhance the immune response. How they work is not entirely understood, but it is postulated that they help keep antigens near the site of injection, meaning that the immune cells can easily access them. Adjuvants are added to vaccines to stimulate the production of antibodies against the vaccine antigen to make it more effective and have been used for decades most often in inactivated (killed) vaccines. There are several hundred different types of adjuvants that are being used or studied in vaccine technology. For example, Aluminium hydroxide and Aluminium phosphate, and there is no evidence of any serious side effects from using them except for occasional minor reactions near the injection site. Adjuvants are also used to reduce the amount of the active component of vaccines.

Antibiotics: These are used during the manufacturing process to prevent bacterial contamination of the tissue culture cells in which the viruses are grown. Usually, only trace amounts appear in vaccines. Commonly used antibiotics include Neomycin and Gentamycin. Persons with known sensitivity to these drugs should be observed for possible reactions after vaccination.

Stabilizers: Stabilizers are used to help the vaccine remain stable and effective during storage. Vaccine stability is important, especially where the cold chain is unreliable. Factors affecting stability include acidity or alkalinity of the vaccine (PH). Stabilizing agents include inorganic salts such as MgCl₂ (for OPV), MgSo₄ (for measles), lactose-sorbitol, and sorbitol –gelatin. Monosodium glutamate and glycine are also sometimes used.

Preservatives and trace components: These are added to multidose and single-dose vaccines to prevent bacterial and fungal growth. They include a variety of substances such as Thiomersal (thimerosal), Formaldehyde or phenol derivatives. Thiomersal is ethyl mercury-containing compound that has generated a lot of debate because of its content, however current evidence shows, there is no evidence of neurotoxicity to Thiomersal (even in trace amounts) in vaccines. Formaldehyde is used to inactivate viruses (IPV) and detoxify bacterial toxins such as those used to make diphtheria and tetanus vaccines.  Although it is purposefully removed during production, the small amounts that remain are too small to cause any harm.

There are strict storage requirements for vaccines. When a vaccine is not safely stored as recommended, its potency is compromised and its use may predispose to the occurrence of adverse events. Hence, there is need to maintain a cold chain. The cold chain or the vaccine supply chain is the system used for storing vaccines in good condition.

The cold chain includes all the materials, equipment and procedures used to maintain vaccines in the required temperature range from the time of manufacture till the vaccines are administered to individuals. Most vaccines require being stored at a temperature range of +2⁰ C to +8⁰ C while others may be frozen.

When a vaccine is kept at temperatures below or above what is recommended by the manufacturer it is termed an “exposed vaccine”. It becomes a “spoiled vaccine” if it cannot be used because of the exposure to temperatures outside +2⁰ C to +8⁰ C for a specific period of time. Temperature monitoring devices which include digital thermometers, data loggers, chart recorders and vaccine vial monitors are used to monitor the temperature of vaccines stored in refrigerators. The fridge could be powered by electricity, solar energy or gas depending on the most available source. Domestic refrigerators are not recommended by World Health Organization for vaccine storage.

Transportation of vaccines is done using insulated containers or cold boxes which have solid walls with a tight lid to maintain the cold chain. It is expected that the insulated containers must be able to store the vaccines at the required temperature for the necessary duration of time. During the vaccination process, the coolant packs must be seen to have some mist around it to ensure they are cold enough (in cases where the temperature monitoring devices are not available).

Different levels (State, local government, ward and Health facility) within the National cold chain system require different types of equipment for storing and transporting vaccines and diluents within the required temperature range.

A cold chain incident occurs when a vaccine is exposed to a temperature higher or lower than the required temperature at any time. This can compromise the potency of the vaccine. Cold chain inspection must be done whenever there is a cold chain incident to find out its cause and determine whether the potency of the vaccine is compromised or not.

Vaccine-preventable diseases are those for which there is a vaccine. These include diseases caused by viruses and those caused by bacteria.

Vaccine-preventable bacterial diseases include tuberculosis, meningococcal disease, pneumonia (due to Streptococcus pneumoniae and Haemophilus influenza type b), pertussis, tetanus, diphtheria, cholera, Typhoid, Lyme disease, tick-borne encephalitis.

Vaccine-preventable viral diseases include Poliomyelitis, Hepatitis B, Hepatitis A, Measles, Yellow fever, Japanese encephalitis, Rabies, Varicella, Diarrhoea due to rotavirus, mumps, rubella, influenza, dengue,  diseases caused by human papillomavirus (cervical cancer, venereal warts)

Although there are many vaccine-preventable diseases, not all of them are recommended in national immunisation programmes. Several factors are taken into consideration before vaccines are recommended. These include;

• Epidemiology of the target disease -incidence, age, sex
• Age-specific morbidity and mortality
• Risk of adverse events from the vaccine
• Cost-effectiveness
• Age of recommended health care visits
• Efficacy of the vaccine

Vaccinations are generally recommended at the age;

• When there is a significant risk of disease and complications
• When the protective immunologic response is expected to occur
• Also recommended for special situations e.g. SCA, HIV

Expanded Programme on Immunisation

The Expanded Programme on Immunisation (EPI) is the World Health Organization’s immunisation programme. The programme started in 1974 with the intention of providing vaccines to all the children in the world. It initially addressed six killer diseases in children. These six diseases tuberculosis, diphtheria, pertussis, tetanus, poliomyelitis and measles were responsible for a high proportion of childhood mortality. With the success of the EPI in reducing morbidity and mortality from these diseases over the years, other diseases have been targeted with the addition of pneumococcal conjugate vaccine, hepatitis B, yellow fever, HPV and meningococcal vaccines to the schedule. The Expanded Programme on Immunisation is now known as Essential Programme on Immunisation with increase in the number of diseases covered and the age group covered to include children, adolescents and adults

• Most low and middle-income countries subscribe to the EPI schedule and countries are encouraged to add on other vaccines depending on the epidemiology of their diseases. Nigeria also subscribes to the EPI and her immunisation programme is called the National Programme on Immunisation (NPI) in which vaccines are provided free for all children.

BCG VACCINE

Bacille Calmette Guerin (BCG) is the vaccine given to children and / or adults to prevent Mycobacterium tuberculosis infection. In infancy, it is given soon after delivery, usually within the first 48 hours, intradermally, and  in the upper arm of the baby. The dose is 0.5 millilitre and this protects against severe forms of tuberculosis for life. The vaccine is very safe.

OPV and IPV VACCINES

Polio, also known as poliomyelitis, is a highly infectious disease caused by the poliovirus types 1, 2 and 3. The virus attacks the nervous system, leading to acute flaccid paralysis and muscle weakness (spinal Polio), and difficulty swallowing, breathing, and speaking (bulbar Polio). Two types of vaccines are given to prevent polio. The Oral Polio Vaccine (OPV). The vaccine has helped eradicate polio in Nigeria, a status achieved in 2020 and it is safe. OPV is given orally as 2 drops per dose, and infants receive it at birth (OPV 0), 6 weeks (OPV 1), 10 weeks (OPV 2), and 14 weeks (OPV 3). However, the battle is not yet over, as vaccine-derived poliovirus (cVDPV) cases continue to be reported due to low population immunity as a result of low immunisation coverage. A single case of poliomyelitis is currently considered an outbreak.

To strengthen the immune system, Inactivated Polio Vaccine (IPV) is also given  along with OPV and protects against all types of polio viurses {Wild types 1,2,3, Vaccine-derived Polio Virus (cVDPV) and Vaccine associated paralytic poliomyelitis (VAPP)}.  IPV  is given as two doses of  0.5ml intramuscularly at the anterolateral aspect of right thigh (2.5cm apart from PCV) at 6 weeks and 14 weeks.

HEPATITIS B VACCINE

Hepatitis B is a viral disease that primarily affects the liver causing severe damage to the liver and its functioning. If left untreated, hepatitis B infection can lead to liver cirrhosis and hepatocellular cancer. Hepatitis infection can be contracted following contact with human and bodily fluids, sexually or through blood transfusion. The vaccine is given 3 times at intervals to achieve lifelong immunity against the disease. It is safe and given as intramuscular injection.

DIPHTHERIA VACCINE

Diphtheria is a life-threatening infection caused by Corynebacterium diphtheriae a bacteria that is transmitted through airborne  respiratory droplets, contact with respiratory secretions of cases or with secretions from infected skin lesions. Diphtheria presents with an adherent membrane which may be present on the tonsils, pharynx, nostrils and on skin ulcers. When it affects the respiratory system it may cause respiratory obstruction leading to death. The exotoxin from the bacteria may affect the heart causing fatal myocarditis. Case fatality is up to 20% when diphtheria antitoxin the mainstay of management is unavailable. Diphtheria antitoxin is often in limited supply hence prevention by vaccination is the best option.

Diphtheria is preventable by the administration of a diphtheria toxoid containing vaccine administered in 3 doses given 4-8 weeks apart as a primary series. Booster doses are then given in the second year of life, at 4-7 years and in adolescence at 9-15 years. Diphtheria toxoid containing vaccines include Td, DT, dTap, DTap, DPT, pentavalent and hexavalent vaccines

PERTUSSIS VACCINE

Pertussis, also called whooping cough, is a highly infectious disease affecting the respiratory tract. It is caused by the bacterium Bordetella pertussis. It remains one of the leading causes of vaccine preventable deaths worldwide. It is spread easily from one person to another mainly through droplets produced by coughing or sneezing. The disease is characterized by numerous bouts of severe coughing, often accompanied by a whoop and post-tussive vomiting.  Vaccination is the mainstay of prevention.

There are two main types of pertussis vaccine: whole-cell and acellular vaccines. The whole-cell vaccine is about 78% effective while the acellular vaccine is 71–85% effective. The effectiveness appears to decrease by between 2 and 10% per year after vaccination, with a more rapid decrease with the acellular vaccines. The pertussis vaccine is available in combination with tetanus and diphtheria vaccines (DPT vaccine) and other antigens (hepatitis B, haemophilus influenza type B) as pentavalent vaccine and injectable polio vaccine as hexavalent vaccine. This is given as a 3 dose series at 6, 10 and 14 weeks of age but booster doses are recommended as the efficacy wanes over the years.

Side effects when they occur are mostly mild and include pain and swelling at the injection site, fussiness, vomiting and feeling weak. Severe side effects are rare and may include convulsions, collapse or shock-like state, anaphylaxis, neurologic deficit etc. Children who have had any of the severe symptoms are not recommended to receive subsequent dose of any pertussis containing vaccines again.  

TETANUS VACCINE

Tetanus was a major killer of newborn children in the early 1980s and beyond until vigorous campaign for immunisation reduced the mortality rate from this disease. Tetanus causes high-grade fever, spasms of the newborn with the occasional cessation of breath, and death. Mothers and all girls in the reproductive age group are encouraged to receive at least 3 doses of the vaccine before delivery and pregnancy.

To prevent tetanus in the child after the newborn period all children should receive 3 doses of tetanus toxoid containing vaccine given  4-8 weeks apart as a primary series while boosters are given in the second year of life, at 4-7 years and at 9-15 years. Tetanus toxoid containing vaccines include Td, DT, dTap, DTap, DPT, pentavalent and hexavalent vaccines.

HAEMOPHILUS INFLUENZAE TYPE B VACCINE

Haemophilus influenzae type B vaccine prevents infection by Haemophilus influenzae type b (Hib) infection which causes pneumonia, meningitis, otitis medi and epiglottitis. The vaccine may be available as a single antigen or in combination with other antigens. In Nigeria it is administered in a combination vaccine known as pentavalent vaccine which contains 4 other antigens- tetanus, diphtheria, pertussis and hepatitis B. The pentavalent vaccine is administered at 6, 10 and 14 weeks. The vaccine is safe with only mild side effects. Severe side effects are extremely rare.

PNEUMOCOCCAL VACCINE

Pneumococcal vaccine was introduced into the immunisation schedule in 2014, and it is given to induce immunity against the pneumococcal organism that causes respiratory infection and meningitis, which is a major cause of childhood illness and death. The vaccine is safe and is given as an intramuscular injection.

ROTA VIRUS VACCINE

Diarrhoeal diseases are one of the commonest causes of death in Nigeria, and the commonest cause of this diarrhoea is rotavirus. The Rotavirus vaccine is given orally and it is safe for all babies. Most babies who receive rotavirus infection do not have any problems but some mothers have reported diarrhoea following administration of the vaccine, and this usually stops within a day.

MEASLES VACCINES

The measles virus causes a constellation of symptoms and signs, fever, rash, cough, runny nose, and red, watery eyes. Complications can include ear infection, diarrhea, pneumonia, brain damage, and death. It is usually given after 6 months of age because maternal immunity transferred to the baby starts waning at that time. Measles vaccine may be given as a single antigen or in combination with other antigens such as Measles Rubella (MR), Measles Mumps Rubella (MMR) or Measles, Mumps, Rubella and Varicella (MMRV)

MUMPS VACCINE

Mumps virus infection causes painful swelling in the jaw with fever. However long term complications of Mumps infection include disease of the testes and ovaries causing the possibility of infertility, and some have reported deafness and meningitis. The vaccine is safe and given in combination with measles and rubella.

RUBELLA VACCINE

Rubella vaccine gives immunity against rubella virus infection which causes fever, rash, and occasionally, deafness and if a woman is infected with the virus when she is pregnant, she may have a miscarriage, and her baby may be born blind, and have some other defects. The vaccine is safe and provides long term immunity.

YELLOW FEVER VACCINE

Yellow fever virus infection is one of the viral haemorrhagic diseases that cause bleeding into various organs of the body in its severest form. Adults can also take this vaccine.  The immunity from this vaccine is long-lasting and WHO recommends a single dose for life

MENINGITIS VACCINE

Meningitis is a serious infection of the meninges, the membranes that surround the brain and spinal cord. It can be caused by bacterial, viral, and fungal organisms. Bacterial meningitis is a life-threatening condition, and symptoms include fever, stiff neck, vomiting, irritability, and headache. Meningitis can lead to complications such as hearing and vision loss, seizures, learning disabilities and behavioural problems, brain damage, and even death.

A major bacterial cause of meningitis is Neisseria meningitides. It has 12 several serotypes  of which the most prevalent are A, B, C, W, X and Y. Men A conjugate vaccine protects against serotype A while the quadrivalent and pentavalent vaccines are protective against 4(A, C, W and Y) and 5 (A, C, W, Y and X)serotypes respectively. The different meningitis vaccines are safe.

MALARIA VACCINE

Malaria is a major cause of morbidity and mortality amongst under-fives. Despite existing interventions such as the use of long-lasting insecticide treated nets, indoor residual spraying with insecticides, about 200,000 Nigeria children still die from malaria every year. The R21/Matrix-M malaria vaccine being used in Nigeria immunisation programmes is given to children to further protect them from malaria and its complications. It is a safe vaccine given intramuscularly at 5, 6, 7 months and a fourth at 15 months.

TYPHOID VACCINE

Typhoid fever, also known as enteric fever, is a bacterial infection caused by Salmonella typhi. It is spread faeco-orally through ingestion of contaminated food or water. Human-to-human spread can occur from contact with a chronic carrier.  Infections are closely associated with poor hygiene practices. Typhoid fever remains endemic in many countries especially in the sub-Saharan and Asian regions. It is estimated that the mortality caused by typhoid fever reaches 7.2 per 100,000 population in sub Saharan Africa. The emergence of resistance to commonly used antibiotics emphasizes the need and relevance of preventive measures including improved sanitation and water supply, ending open defaecation and also vaccination for at risk individuals including children and travelers.

Vaccines include the Oral typhoid vaccine (Ty21a vaccine) which provides around 50-90% protection against typhoid fever with efficacy of up to 5 years and the Injectable vaccine (Typhoid conjugate vaccine) which provides up to 90% protection against Typhoid fever with efficacy up to 2 years. Side effects of the vaccines include diarrhoea and abdominal discomfort following the oral vaccine, while redness  ,pain and swelling may follow vaccination with the injectable vaccines

INFLUENZA (FLU) VACCINE

Influenza (often called “flu”) is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs. Influenza can cause mild to severe illness and, at times, can lead to death. Symptoms of influenza include fever and chills, sore throat, muscle aches, fatigue, cough, headache, and runny or stuffy nose. Vomiting and diarrheoa may also occur in children.

Infants and young children, people 65 years and older, pregnant women and people with certain health conditions or weakened immune system are at greatest risk of flu complications such as Pneumonia, Bronchitis, sinus infections, and ear infections are examples of flu-related complications.

There are different types of influenza vaccine – inactivated influenza vaccine and live  influenza vaccine. Influenza vaccines are constantly updated each year to protect against the influenza viruses that are expected to spread during the next influenza season.

Influenza vaccines are safe with only mild side effects such as soreness, redness and swelling at the injection site. There is a small increased risk of Guillain-Barre syndrome following injection of the inactivated vaccine.

Influenza vaccine is contraindicated for those under six months of age and those with severe, life-threatening allergies to flu vaccine or any ingredient in the vaccine.

CHOLERA VACCINE

Cholera is an infection caused by a bacterium, vibrio cholerae. It is spread through water and food contaminated with the cholera bacteria. It can cause life-threatening watery diarrhoea and vomiting. Cholera vaccines help to prevent the infection. Two doses of the bivalent cholera vaccine at a dose of 1.5mls are administered orally, at least 14 days apart to individuals of aged one year and older. A single dose may be administered in certain situations. Two doses of the vaccines provide protection against cholera for 3 years, while a single dose provides short term protection. Cholera vaccine is safe but rare side effects of nausea, vomiting, abdominal cramping, headache and loss of appetite may occur.

HUMAN PAPILLOMAVIRUS VACCINE

Chronic infection with the Human Papillomavirus (HPV) is responsible for more than 90 percent of cases of cervical cancer. The virus is also responsible for other cancers like vaginal, vulvar, penile and oropharyngeal cancers. The HPV is responsible for genital warts. The timing between the infection with HPV and the manifestation of the cancer usually takes decades. The HPV vaccine is effective in the prevention of infection with the dangerous strains of HPV (specifically strain 16 and 18 that are responsible for about 70 percent of cervical cancer). This vaccine is most effective when given before sexual debut. A single dose of the HPV vaccine is recommended for children from 9 to 14 years according to the Nigerian routine immunisation schedule. Also, a single or two doses (six months apart) of the HPV vaccine is recommended for adolescents and adults between 15 to 20 years, and two doses (with six month interval) is recommended from 21 years and above. Two to three doses are recommended for immunocompromised individuals. The commonest side effects of the HPV vaccine are pain, swelling and redness at the injection site, which resolve within one to three days.

VACCINE SAFETY NET

The vaccine safety net is a WHO-initiated programme aimed at improving the information available to the general public concerning immunisation in children, in terms of content, and context to prevent undue fear about the safety of vaccines.
The VSN is established to provide understandable, evidence-based information on the safety of vaccines for internet users, regardless of their geographic location and language. Not too long ago, some infants were denied vaccines because their parents were misinformed about the intentions behind the immunisation. PAN partners with VSN to provide safe and effective vaccines and information to the general public and medical practitioners.

Despite the proven benefits of immunisation, Nigeria still struggles with vaccine-preventable diseases and perennially low immunisation coverage. Peculiar challenges have continued to threaten the gains made in the fight against Vaccine-Preventable Diseases. Among these challenges are inadequate funding of health services, religious beliefs and misconceptions regarding vaccines and vaccine safety, and weak access to health services. These factors, singly and in combination, lead to the low immunisation coverage in the country.

Health services including immunisation services are poorly funded in Nigeria. Significant funding for the country’s vaccination programme comes from external donors. Due to the tenuous funding, many vaccines are not given on demand. In some cases, clients are pooled to a minimum number below which a vial is not opened even though this practice is not in accordance with the National policy. On occasions, vaccines have been reported unavailable to clients due to breaches in the supply system, leading to the postponement of due immunisations. These practices result in missed opportunities.

In the last decade, the Nigerian healthcare landscape has been bedeviled with strikes from health workers; these strikes have had a negative impact on immunisation coverage as often clients have been turned away at such periods of strikes which occur rather too often.

Religious and political considerations have also posed challenges to our vaccine programme. In 2003, protests and boycotts followed the introduction of some vaccines in the northern part of Nigeria owing to rumors of population control through such vaccines. This boycott contributed to the persistence of poliomyelitis for many years after. Apart from religion, there have been unfounded misrepresentations about vaccine safety owing to ignorance among the populace. General practice is to refrain from seeking immunisation during minor illnesses. In addition, unrelated deaths have been attributed to immunisations thereby reducing confidence in vaccine services.

Another major challenge to immunisation is the operations of Boko haram terrorists, bandits, and other forms of insecurity in some parts of the country which has resulted in many children being orphaned or being in internally displaced persons (IDP) camps. Healthcare workers and volunteers providing services to these IDPs are also abducted and sometimes killed. These factors result in a reduction in available healthcare workers, logistic challenges in transportation, and storage of vaccines, and the children are either not vaccinated or are vaccinated late. There is, therefore, an urgent need to curb the insurgencies and insecurity in these parts of the country to improve access to immunisation

The Covid-19 pandemic resulted in limited access to immunisation services through the lockdowns and revived a number of conspiracies regarding vaccine safety. Worse still health care workers including paediatricians have become vaccine hesitant. This situation has continued to threaten efforts to reduce under-five mortality in Nigeria. The government should, therefore, strive to restore the confidence of the populace in vaccines, as well as provide continuing education of the masses on the proven safety and efficacy of current vaccines. PAN continues to provide support in this regard not only for her members but also for health care workers in general and for the general population. In addition, there should be increased funding of health services to reduce the reliance on foreign support to maintain immunisation services in the country.

The presence of a contraindication increases the risk of developing an adverse reaction to a vaccine recipient, in such a case the vaccine should be withheld. Contraindications are rare (and usually temporary) but misperceptions that they occur frequently lead to refusals to take vaccines and poor immunisation coverage.

The only true contraindication to all vaccines is a previous serious allergic reaction (anaphylaxis) to an earlier received vaccine dose or constituent. Non-absolute contraindications include:

• Severe immunocompromised persons: do not give live vaccines.
• Pregnancy: do not give live attenuated vaccines.
• Occurrence of encephalopathy within 7 days of receipt of a pertussis-containing vaccine which cannot be attributed to another identifiable cause: do not give any other dose of a pertussis-containing vaccine.
• Severe Combined Immunodeficiency (SCID) disease and a history of intussusception: do not give rotavirus vaccines.

Other conditions that can increase the risk of adverse reactions, cause diagnostic challenges, or prevent the production of immunity after vaccination are precautions. The risk from precautions is less than those from contraindications. Where there are precautions, the vaccine should be given if the benefits outweigh the risks but should preferably be deferred until the earliest suitable time. Precautions should be taken in the presence of:

• moderate or severe acute illness with or without fever.
• a family or personal history of seizures (for MMRV vaccine).
• a neurologic disorder
• development of Guillain-Barre Syndrome within 6 weeks after receiving a previous tetanus toxoid –containing vaccine dose or influenza vaccine.
• egg allergy (excluding hives) for the influenza vaccine.
• receipt of antibody-containing blood products within 11 months or less for the varicella vaccine.
• receipt of specific antiviral drugs (acyclovir, famciclovir, vacyclovir) 24 hours before vaccination and 14 days after vaccination for varicella and zoster vaccine

Note that BCG or yellow fever should not be given to infants with symptoms of HIV/AIDS. Health workers should also be taught to recognise signs of adverse reactions and report such reactions to their superiors immediately.

1. Vaccine Safety basics. https://vaccine-safety-training.org/vaccine-components.html#:~:text=Vaccines%20include%20a%20variety%20of,products%20from%20the%20production%20process.{Acessed 14^th August 2020}
2. Centers of Disease control and prevention https://www.cdc.gov/vaccines/hcp/index.html{Acessed 14^th August 2020}
3. Public Health: What goes into a vaccine? https://www.publichealth.org/public-awareness/understanding-vaccines/goes-vaccine/{Acessed 14^th August 2020}
4. UNICEF (2020). Immunisation- current status and progress. [Online], Available: https://data.unicef.org/topic/child-health/immunisation/[Accessed 18/8/2020]
5. PAN advisory committee on Immunisation. Paediatric Association of Nigeria (PAN) recommended routine immunisation schedule for Nigerian children. Niger J Paed 2012;39(4):152-158
6. National Primary Health Care Development Agency. Training manual for the introduction of meningococcal A conjugate vaccine(Men A) in routine immunisation in Nigeria. June 2019.
7. World Health Organisation. Vaccine safety basics e-learning course. Module 2. 2020 Available online at https://vaccine-safety-training.org/contraindications.html last accessed 17 August, 2020.
8. Centre for Disease Control. Vaccine recommendations and guidelines of the ACIP. 2020. Available online at https://www.cdc.gov/vaccines/hcp/acip-recs/general-recs/contraindications.html last accessed 17 August, 2020.
9. Rubin L, Levin M, Ljungman P, et al. 2013 IDSA clinical practice guideline for vaccination of the immunocompromised host. Clin Infect Dis 2014;58(3):e44-100. DOI: 10.1093/cid/cit684
10. Kroger A, Atkinson W, Pickering L. General immunisation practices. In: Plotkin S, Orenstein W, Offit P, eds. Vaccines. 6th ed. China: Elsevier Saunders; 2013:88-111.
11. Addition of history of intussusception as a contraindication for rotavirus vaccination. MMWR Morb Mortal Wkly Rep. 2011;60(41):1427.
12. Marin M, Broder KR, Temte JL, Snider DE, Seward JF. Use of combination measles, mumps, rubella, and varicella vaccine: recommendations of the Advisory Committee on Immunisation Practices (ACIP). MMWR Recomm Rep. 2010;59(RR-3):1-12.
13. Grohskopf LA, Sokolow LZ, Olsen SJ, et al. Prevention and Control of Seasonal Influenza with Vaccines Recommendations of the Advisory Committee on Immunisation Practices — United States, 2016–17 Influenza Season. MMWR Recomm Rep 2016;65(No. RR-5):1-54.
14. McLean HQ, Fiebelkorn AP, Temte JL, Wallace GS. Prevention of measles, rubella, congenital rubella syndrome, and mumps, 2013: summary recommendations of the Advisory Committee on Immunisation Practices (ACIP). MMWR Recomm Rep. 2013;62(RR-4):1-34.
15. Marin M, Guris D, Chaves SS, Schmid S, Seward JF. Prevention of varicella: recommendations of the Advisory Committee on Immunisation Practices (ACIP). MMWR Recomm Rep. 2007;56(RR-4):1-40.
16. Harpaz R, Ortega-Sanchez IR, Seward JF. Prevention of herpes zoster: recommendations of the Advisory Committee on Immunisation Practices (ACIP). MMWR Recomm Rep. 2008;57(RR-5):1-30; quiz CE32-34.
17. National Primary Health Care Development Agency, Nigerian Field Guide on surveillance of adverse events following immunisation (AEFI) and response. 2018
18. Sadoh A, Onuchukwu C, Mukhtar-YolaM, Ekop E, Iregbu F, Medupin P, Bisi-Onyemaechi A, Teru P, Maduka O, Fajolu I, Yilgwan C, Olatunya O, Okafor A, Oniyangi O, (members of Child Health Watch sub-committee) PAN Immunization homepage .Long life for all. Available at https://pan-ng.org/immunization-page/ Accessed 18^th June 2025

This document was originally prepared by members of the child health watch committee of PAN but has been updated by members of the PAN Subcommittee on Immunisation. (Updated June 2025)

Dr  Ayebo Sadoh – Chair person

Dr  Esther Yiltok – Secretary

Dr Folusho Balogun – Member

Dr Abigail Dodo– Member

Dr Dorothy Esangbedo – Member

Dr Boboye Ifie-Ombeh – Member

Dr Patricia Medupin– Member

Dr Tamunoiyowuna Okari – Member

Dr Somkenechi Okpala– Member

Dr Peter Teru– Member