Nigerian Journal of
Paediatrics 2011;38 (4):186 - 194
SYMPOSIUM
Abdulkarim AA
Vaccines and immunization: The past,
Ibrahim RM
Fawi
AO
present and future in Nigeria
Adebayo OA
Johnson A'WBR
Received: 24th October
2011
Abstract Vaccines
are arguably
The scientific world is
still
Accepted: 24th October
2011
the most important
public health
searching for
appropriate candidate
tools available today.
Since the
vaccines for malaria
and HIV
Abdulkarim AA (
)
successful eradication
of small-
infection. Despite the
availability
Ibrahim RM, Fawi
AO
pox with the use of the
vaccine,
and effectiveness of
many vaccines,
Adebayo OA, Johnson
A'WBR
many vaccines have
become
the benefits to a
country is highly
Department of
Paediatrics and
available to man. Of
great
dependent
on
a
viable
and
child Health,
University of Ilorin
importance to public
and child
sustainable health
system which
Teaching
Hospital
health are the vaccines
against the
include
adequate
financing,
E-mail:aishaakarim@yahoo.com
so-called six killer
diseases of
dynamic and motivated
workforce,
Tell:
+2348033734509
childhood- measles,
pertussis,
strong partnerships and
effective
diphtheria, tetanus,
tuberculosis
community
participation. If well
and poliomyelitis. In
the last 2
deployed, available
vaccines as
decades, effective
vaccines against
elucidated in this
discourse can
the major causes of
pneumonia,
accelerate the
achievements of the
another childhood
killer, have
Millennium Development
Goals in
become available. Data
from many
Nigeria and many other
developing
parts of the world
including
countries.
African countries have
shown the
benefits of the pneumococcal and
Key
words :
Vaccines,
Haemophilus
influenzae
type
b
Immunizations,
Nigeria.
vaccines.
Introduction
Candidate vaccine :
Any vaccine
for which
the
development was
foreseeable with the next decade.
Immunity :
Protection from
microbes recognized
as
Vaccine efficacy :
A population
based measure
of
foreign. The immune
system is composed of organs
protection rather than
a measure of antibody
& specialized cells
that protect the body by
production in an
individual. This is represented by the
identifying harmful
substances & destroying them
equation below:
using anti-bodies, and
other specialized substances
Rate of illness in
unvaccinated population Rate of
& cells.
illness in vaccinated
population
Rate of illness in
unvaccinated population
Primary immune response :
Following antigenic
challenge antibodies,
specific helper and effector T
Vaccine preventable illness : Is
that portion
of disease
lymphocytes including
those producing cytokines
burden that could be
prevented by immunization of
and killer T cells are
produced.
entire target
population with hypothetical vaccine
100% effective against
the strain included in it.
Vaccine :
Any preparation
intending to
produce
immunity to a disease
by stimulating the production
Vaccination :
Is the
administrations of
antigenic
of antibodies. Can
prevent or ameliorate the effect of
materials to produced
immunity to a disease. It was
infections by many
pathogens. Most common
originally used
specifically to describe the injection
method of
administration is by injections, but can be
of small pox.
given orally or by
nasal spray.
187
Immunization :
A process
of artificial
induction of
Types of Vaccine
immunity in an effort
to protect against infectious
disease.
Inactivated Vaccine: Consist of
virus particles
which
are grown in culture
and then killed using heat or
Active Immunization :
Induces in
the recipient
a
formaldehyde. These
particles are destroyed but
degree of immunity
similar to that achieved from the
capsid proteins are
intact enough to be recognized and
natural infection, and
is able to prevent clinical
remembered by immune
system, thus evoking a
disease. Produced by
individual immune system and
response. It is
non-replicating, with less interference
the immunity are
usually long lasting.
from circulating
antibodies. Requires more doses and
causes a mostly humoral
immune response. The
Passive
Immunization :
Is the
administration of
antibody titre
diminishes with time.
exogenously preformed
antibodies, and the immunity
is temporary. Commonest
source is that obtained
Examples of inactivated
vaccines include:
transplacentally. Others
are blood and blood
products, immune or
hyper immune globulin &
Viral- poliomyelitis
(salk) hepatitis A, Rabies,
animal
antitoxin.
influenza
Bacteria- pertussis,
typhoid, cholera, plague,
Toxoid :
This is
made from
purified toxins
produced
anthrax
by infective agent,
attenuated to neutralize this toxic
Fractional subunit
hepatitis B, acellular
effect without reducing
antigenicity e.g tetanus
pertussis, human
papilloma virus
toxoid, diphtheria
toxoid.
Toxoids diphtheria,
tetanus
Potency :
Ability of
vaccine to
elicit a
particular
Polysaccharide
pneumococcal, meningococcal,
response at a certain
dose in other to work. It is a
salmonella typhi
measure of a vaccine
activity in biological system.
Conjugate
polysaccharide- Hib, pneumococccal,
meningococcal
Clinical trial: A
scientifically designed and
executed
Recombinant hepatitis
b , human papilloma
investigation of the
effects of a drug (or vaccine)
virus, influenza
administered to human
subjects. The goal is to define
the safety, clinical
efficacy, and pharmacological
Immune globulin
homologous pooled
effects
(including
toxicity,
side
effects,
antibody.hepatitis A,
measles
incompatibilities, or
interactions) of the drug.
Homologous human
hyperimmune globulin.
PEP hepatitis B,
rabies, tetanus, varicella
Randomized :
Each study
subject is
randomly
Heterologous
hyperimmune serum(antitoxin):
assigned to receive
either the study treatment or a
antitoxin derived from
injecting animals with
placebo.
the organism such as
for botulism, diphtheria
Monoclonal antibodies
derived from the clone
Blind :
The subjects
involved in
the study
do not
know
of antibody producing
cells, e.g. RSV.-
which study treatment
they receive. If the study is
Palivizumab
double-blind, the
researchers also do not know which
treatment is being
given to any given subject.
Live Attenuated Vaccines: Produced by
modifying a
naturally occurring
organism (wild) usually by
Double-dummy design :
Allows additional
insurance
repeated culturing, and
retains the ability to
against bias or placebo
effect. In this kind of study, all
replicate and produce
immune response similar to
patients are given both
placebo and active doses in
natural infection.
Circulating antibody may interfere
alternating periods of
time during the study.
with response. Provides
long lasting immunity, and
one dose usually
suffices. Examples of live
Placebo-controlled :
The use
of a
placebo (fake
attenuated viruses-
poliomyelitis, measles, rubella,
treatment) allows the
researchers to isolate the effect
mumps, rabies,
varicella, yellow fever, rotavirus,
of the study treatment.
Open-label means that both
influenza. Examples of
live attenuated bacteria-
the participants and
the scientists know what is given.
Bacille Calmette
Guerin, typhoid.
Vector :
Is a
packaging system
that can
help deliver
the
Benefits of Immunization
vaccine more
effectively into the correct part of the
body or into the
correct cell to create an immune
It is a proven tool for
controlling & eliminating
response.
life threatening
infectious diseases (over 2million
deaths per
year).
Insert :
Consists of
some extra
genes added
into the
Avoids suffering,
disability and death.
vector.
One of the most cost
effective health
investment with proven
strategies that make it
188
accessible to most hard
to reach & vulnerable
This process, known as
"variolation," took a variety
population.
of forms. One form
consisted of removing pus and
Can be delivered
effectively through outreach
fluid from a smallpox
lesion and using a needle to
activities.
place it under the skin
of the person to be protected.
Ease strain on health
care system, and money is
The second involved
peeling scabs from lesions,
saved for use in other
health care services.
drying and grinding
them to a powder, and letting an
Has clearly defined
target group.
uninfected person
inhale this powder.
Does not require any
major change in life style.
The third method
involved picking up a small amount
of the scab powder with
a needle and then using the
National Programme on Immunization (NPI)
needle to place the
powder directly into the
individual's veins.
Although the effects of variolation
This was introduced in
Nigeria in 1979. From 1979
varied, ranging from
causing a mild illness in most
1997, the program was
known and called Expanded
individuals to causing
death in a few, the mortality
Programme on
Immunization (EPI). To give a
and morbidity rates due
to smallpox were certainly
national outlook and
show Federal Government
lower in populations
that used variolation than in
commitment, the Federal
Govt. established an agency
those that did
not.
called NPI under Decree
12 in August 1997. This is to
effectively control the
occurrence of all vaccine
Edward Jenner noticed a
relationship between the
preventable diseases
through immunization and
equine disease known as
"grease" and a bovine
provision of vaccine
and other consumable. Focus is
disease known as "cow
pox. “ At the same time,
on prevention, control
& eradication of the following
Jenner was interested
when a milkmaid told him that
vaccine preventable
disease in Nigeria i.e.
she could not catch
smallpox because she had had
tuberculosis, measles,
diphtheria, pertussis, neonatal
cowpox. Jenner noted
that there were many people
tetanus, cerebrospinal
meningitis, yellow fever and
like the milkmaid -
people who milked cows and who
polio. These are
targeted through immunization
did not get smallpox
even when exposed repeatedly.
service delivery and
this is done by administration of
With this in mind,
Jenner undertook a daring
vaccine to susceptible
target.
experiment in
1796:
NPI aim the following
group of people: Children of
It soon became clear
that Jenner's experiments had
age ≤ 11month, all
pregnant women and women of
paid off, and that
intentional infection with cowpox
reproducing age
group.
protected people from
much more serious infection
with smallpox. As a
result, within a few years
Immunization schedule in Nigeria
thousands of people
protected themselves from the
deadly smallpox disease
by intentionally infecting
Birth OPV , HBV ,
BCG
0
1
themselves with cowpox.
Jenner's process came to be
6weeks OPV , DPT ,
HBV
1
1
2
2
called "vaccination,"
after "vacca," the Latin word for
10weeks OPV ,
DPT
2
cow, and the substance
used to vaccinate was called a
14weeks OPV , DPT ,
HBV
3
3
3
"vaccine."
9months Measles,
Yellow fever, Vitamin A
1
15 months- Vitamin
A
2
Now, over 200 years
later, we have progressed from a
time when vaccination
was a rare event, and Jenner's
In pregnant women, or
women in reproducing age
theories about
vaccination were not widely accepted,
group:
to the late 1900s when
vaccines are so commonplace
Tt1 at 1 contact no
protection
st
that most children
receive multiple vaccinations
TT2 4wks later 80%
protection for 3years
before they reach their
first birthdays. The result of
such widespread
vaccination has been a marked
TT3 6mths later 95%
protection for 5 years
decrease in diseases
which once ravaged the world's
TT4 1year later or in
subsequent pregnancy
population.
99% protection for 10
years
Tt5 1 year later or in
subsequent pregnancy 99%
Below is the timeline
of some vaccines:
protection for
life
1721- Introduction into
Britain from Turkey by
Lady Wortley Montagu of
inoculation of material
History and impact of immunisation
from smallpox patients
into healthy persons
(
variolation )
Long before the causes
of disease were known and
1796 -First vaccination
against smallpox
the processes of
recovery were understood, the
performed by
Jenner
Chinese trial of
exposing uninfected individuals to
matter from smallpox
lesions was used.
1881 -Pasteur, Roux,
and Chamberland
introduced anthrax
vaccine
189
1885 -Pasteur developed
rabies vaccine
Polio: Global
coverage of
infants with
three doses
of
1895 -Yersin produced
plague vaccine
polio vaccine in 2008
was 83%, but in 1990 it was
1898 -Almroth Wright
developed typhoid
75%. Reported number of
polio cases in 2008: 1730
vaccine
confirmed polio cases
(including 1651 wild virus
confirmed cases) as
against 350 000 in 1988. The
1921 -Calmette and
Guérin introduced BCG
number of polio-endemic
countries in 2008 was 4, as
vaccine
against 125 in
1988.
1923 -Ramon developed
diphtheria toxoid
1927 -Ramon and Zoeller
developed tetanus
Measles: Global
coverage of
children by
their second
toxoid
birthday with one dose
of measles containing vaccine
1940 -National
immunization campaign
in 2008: 83%, while the
global coverage of children
launched in Britain by
Ministry of Health; did
by their second
birthday with one dose of measles
not become widespread
until 1942
containing vaccine in
1990: 73%. Number of
1954 -
Salk (killed) polio vaccine introduced
countries with a second
dose of measles vaccine in
1957 -
Sabin (live) polio vaccine introduced
routine immunization
schedule: 133 (69% of 193
1960 -Measles vaccine
developed by Enders
countries). Number of
estimated measles deaths in
1962 -Rubella vaccine
developed by Weller
2007: 197 000 [141 000
- 267 000], of which 177 000
[126 000 - 240 000]
were under age five.
1967 -Jeryl Lynn strain
of live attenuated
mumps vaccine licensed
in the US
Maternal and Neonatal Tetanus : The
number of
1968 Meningococcal
(type C) vaccine
countries that had not
yet eliminated MNT in 2008
developed. Measles
vaccine introduced on a
was 46. Number of women
living in high-risk areas
national scale in
Britain
protected with at least
two doses of tetanus toxoid
1970 -Rubella vaccine
became available in
vaccine given during
supplementary immunization
Britain
activities (1999-2008):
90 million.
1981 -Hepatitis B
vaccine licensed in US
1988 -Measles, Mumps,
Rubella (MMR)
Hepatitis B: Global
coverage of
infants with
three
vaccine introduced into
Britain
doses of hepatitis B
vaccine in 2008 had increased to
1992 -Haemophilus
influenzae b (HiB) vaccine
69% from 1% in
1990.
introduced into
Britain
Increasing uptake of
new and underused vaccines
Global Immunization Data
Hepatitis B vaccine :
The use
of this
vaccine for
Based
on
the World
Health
Organization
infants was introduced
nationwide in 177 countries
(WHO)/UNICEF global
estimates for 2008, trends
(including in parts of
India and the Sudan) by the end
related to global
vaccination coverage continue to be
of 2008, up from 171
countries in 2007. Global
positive. Immunization
currently averts an estimated
hepatitis B vaccine
coverage is estimated at 69% and
2.5 million deaths
every year in all age groups from
is as high as 89% in
the Western Pacific and 88% in
diphtheria, tetanus,
pertussis (whooping cough), and
the Americas. Coverage
in the South-East Asia
measles. More children
than ever before are being
Region increased from
29% to 41%, over the same
reached with
immunization. In 2008, an estimated
period. Haemophilus
influenzae type B (Hib) vaccine
106 million children
under the age of one were
was introduced nationwide
in 136 countries
vaccinated with three
doses of diphtheria-tetanus-
(including in parts of
Belarus, Pakistan and the
pertussis (DTP3)
vaccine.
Sudan) by the end of
2008, from 115 countries in
2007. Global coverage
with three doses of Hib
More countries achieve
high levels of vaccination
vaccine is estimated at
28% in 2008, reaching 90% in
coverage. Three
regions: the Americas, Europe and
the Americas, but only
4% in the Western Pacific
Western Pacific
maintained over 90% immunization
Region.
coverage. The number of
countries reaching 90% or
more immunization
coverage with DTP3 vaccine in
Maternal and neonatal tetanus (MNT)
: The
vaccine
2008: 120 countries
compared to 117 in 2007. The
to prevent MNT was
introduced as part of routine
number of countries
reaching over 80% DTP3
immunization programmes
in over 100 countries by
coverage in 2008: 151
countries in 2008 compared to
the end of 2008.
Vaccination coverage with at least
150 in 2007.
two doses of tetanus
toxoid vaccine or tetanus-
diphtheria toxoid
vaccine was estimated at 74% in
DPT :
Global coverage
of infants
in 2008
with DTP3
2008 and an estimated
81% of newborns were
vaccine was 82%, while
in 1990 DTP3 vaccine
protected against
neonatal tetanus through
coverage was75%.
Estimated number of children
immunization. As of
December 2008, maternal and
vaccinated with DTP3
vaccine in 2008: 106 million.
neonatal tetanus
persist as public health problems in
46 countries, mainly
inAfrica andAsia.
190
Pneumococcal vaccine: Introduced in
31 countries
Firstly the primary
health care services are highly
(including five
countries where the vaccine was
ineffective and have
deteriorated due to the lack of
partially introduced)
by the end of 2008, up from 20
investment in
personnel, facilities and drugs, and
countries in
2007.
because of poor
management of the existing
resources. A formerly
strong primary health care
Rotavirus
vaccine :
Introduced in
19 countries
system in northern
Nigeria has weakened over many
(including two
countries where the vaccine was
years. Polio outbreaks,
rumors on the safety of the
partially introduced)
by the end of 2008.
polio vaccine, and
subsequent campaigns disrupted
routine
immunization
services.
Routine
Yellow fever vaccine :
Introduced in
routine infant
immunization services
are either no longer available
immunization programmes
in 34 countries and
or irregular; limited
resources for health services and
territories out of the
44 at risk for yellow fever in
gaps in vaccine storage
and distribution add to the
Africa and
theAmericas.
challenge of increasing
immunization coverage.
There is also a problem
of confidence and trust by the
The
unprotected children: The
number of
children
public in the health
services resulting from the poor
under one year of age
who did not receive DTP3
state of the facilities
and low standards of delivery.
vaccine worldwide: 23.5
million in 2008 compared to
These problems have
been exacerbated by “ vertical ”
23.9 million in 2007.
Seventy percent of these
interventions
undertaken by outside agencies which
children live in ten
countries: Chad, China,
undermined the capacity
of the local service
Democratic Republic of
the Congo, Ethiopia, India,
providers to implement
sustainable programmes. At
Indonesia, Iraq,
Nigeria, Pakistan and Uganda.
the family / community
level there is a low demand
for immunization due to
a lack of understanding of its
Deaths due to vaccine-preventable diseases (VPD)
value.
More than 10 million
deaths occur globally in
Development of New Vaccines
children age < 5, of
which 24% are due to VPD. The
total number of
children who died from diseases
A number of new
vaccines with major potential for
preventable by vaccines
currently recommended by
controlling infectious
diseases have just been
WHO, plus diseases for
which vaccines are expected
licensed or are at
advanced stages of development.
soon is 2.5 million.
Distribution is hepatitis B: 600
Among the illnesses
targeted are rotavirus diarrhoea,
000, Hib: 363 000,
pertussis: 254 000, tetanus: 163
pneumococcal disease,
malaria and HIV which
000, others (polio,
diphtheria, yellow fever): 36 000.
together kill more than
a million children each year,
most of them in
developing countries. Vaccine
Estimated number of
deaths in children under five
development proceeds
through discovery, process
from diseases
preventable by vaccines (excluding
engineering, toxicology
and animal studies to human
measles) currently
recommended by WHO is 890 000
Phase I, II, and III,
and IV trials. The process can take
as Hib: 363 000,
pertussis: 254 000, neonatal tetanus:
more than 10 years,
depending on the disease.
128 000, tetanus
(non-neonatal): 16 000, others
(polio, diphtheria,
yellow fever): 19 000.
The
human trials
Estimated number of
deaths in children under five
Phase I focus is on
safety, involving small
due to rotavirus and
pneumococcus: 1.3 million, as
groups of
people(20-100)
pneumococcal disease:
735 000, and rotavirus: 527
Phase II
moderate-sized "target" populations
000.
(persons close to the
age and other xteristics for
whom the vaccine is
intended) to determine
In
Nigeria
both safety and the
stimulation of immune
response
(20-300)
Immunization rates in
Northern Nigeria are some of
Phase III - large
target populations (30-3000)to
the lowest in the
world. According to the 2003
establish whether a
vaccine actually prevents a
National Immunization
Schedule the percentage of
disease as intended
(efficacy) ,
fully immunized infants
on the States to be targeted
Phase IV trial is also
known as post marketing
was less than 1% in
Jigawa, 1.5% in Yobe, 1.6% in
surveillance trial. It
involves the safety
Zamfara and 8.3% in
Katsina.As a result thousands of
surveillance
(pharmacovigilance), and ongoing
children are dying as
victims of vaccine preventable
technical support of a
drug after it receives
diseases.
In many parts of the
north, barely 10
permission to be
sold.
percent of children
receive all of their routine
vaccines. Coverage
rates for the vaccine against
tetanus among women are
equally low. Why?
191
Obstacles to introduction of new vaccines
can spread rapidly from
the tropics to the
industrialized world.
Several diseases of
Falter in the gains of
the EPI of the late 1980s. The
importance to the
developing world are also
initial high worldwide
coverage decreased from
potential bioterrorism
threats.
80% to < 50% of
infants receiving their third dose
The emergence of
public-private partnerships
of DPT, esp. in
sub-SaharanAfrica.
(PPPs). PPPs are
coordinated by nonprofit
Increasing divergence
between vaccine products
organizations that
raise money from the public
used in the
industrialized versus developing
sector and use this
money to leverage efforts by
worlds. This
divergence
include
newer
both the public and the
private sectors to develop
generation vaccines,
several vaccines and
and produce affordable
vaccines for the
vaccine formulations
that had formerly been used
developing world. PPPs
are involved in
jointly in
industrialized and developing country
accelerating the
development of vaccines against
populations ceased to
be recommended in
malaria, tuberculosis
and HIV. Examples of PPP
industrialized
countries.
are the International
AIDS Vaccine Initiative, the
Little incentive for
the vaccine industry in the
AERAS Global TB Vaccine
Foundation, the
industrialized world to
develop new vaccines
Malaria Vaccine
Initiative, and the Global
Alliance for Vaccines
and Immunization (GAVI)
.
against diseases that
were largely limited to the
developing world, as
industrialized world
The emergence of high
quality vaccine producers
markets are more
lucrative.
and capable national
regulatory authorities in the
The increasing
stringency of regulations imposed
developing world. In
Brazil, Cuba, India and
by national vaccine
licensing authorities usually
Indonesia certain
manufacturers have been
result in an increase
in the costs of clinical
prequalified by the
World Health Organization to
development pathways
for licensure of vaccine
supply EPI vaccines for
purchase by United
candidates to hundreds
of millions of dollars.
Nations agencies. Due
to location and the
New generation vaccines
would have to cost
available market of
selling vaccines, the void of
dollars per dose in
order for industry to recover an
the increasing
departure of the international
adequate return on its
investmentin contrast to the
companies is being
filled.
pennies per dose cost
of the traditional EPI
vaccine.
New
and Underused Vaccines in Developing
It had become
increasingly common to find that
Countries
vaccines performed less
well in developing
Typhoid fever Vaccine
country populations
than in populations residing
in the industrialized
world. Trials of vaccines in
S.
typhi vaccine
developed in1896,
heat-killed,
developing countries
were needed before their
phenol-preserved,
injectable whole-cell, still licensed
introduction in these
settings, and trials in
in several countries
despite its high reactogenicity.
developing countries -
not a priority for large
producers in the
industrialized world. If they were
Two new vaccines are
currently licensed and widely
undertaken, they were
typically deferred for years
used worldwide, a
subunit (Vi PS) vaccine given via
after vaccine licensure
in industrialized
the intramuscular
route, andTy21a- a live attenuated
S typhi strain given
orally.
Opportunities for vaccine introduction
The
Vi polysaccharide vaccine :
Administered as
one
dose (25g) via the
IM/SC route. It is given to school-
To overcome the
disincentives to industry of
aged children and
protective for at least three years,
creating new vaccines
for the developing world,
with a good safety
profile. It is poorly immunogenic
Governments in the
industrialized world have
in infants and not used
in children less than 2 years of
traditionally used
'push mechanisms. Push
age.
mechanisms - aim is to
lower the risks and costs to
industry of research
and development, and
The
Ty21a vaccine :
The first
live oral
typhoid fever
includes;
providing
grants
for
product
development, supporting
the costs of clinical
vaccine, administered
as enteric-coated capsules to
trials, strengthening
of field sites in developing
be swallowed every
other day for one week. The
countries, providing
research and development
vaccine is protective
for at least 5-7 years.
tax credits and
expediting the regulatory and
licensing
process.
Rotaviruses (RV) Vaccine
Increased funding- major
contributors are
Rotavirus diarrhoea is
a leading cause of severe
foundations. This is
due to the increasing
diarrhoeal disease and
dehydration in infants and
recognition that
infectious diseases are major
under-5 yrs children
globally. Three oral RV vaccines
threats to global
security, and infectious diseases
are currently
licensed.
192
Human monovalent live
attenuated RV strain,
Pneumococcal conjugate vaccines (PCV):
The first
PCV, Prevnar
TM
Rotarix , given as a
2-dose monovalent oral
TM
(Wyeth), is recommended
for routine
vaccine.
use in children aged
less than two years. It is
Pentavalent live
bovine-human reassortant
administered in a 3
doses schedule, and when
vaccine, RotaTeq , a
live-attenuated, 3-dose
TM
possible in combination
with usual routine
oral vaccine. Part of
national vaccination
vaccination, followed
by a booster dose at 15-18
programs in several
countries, including USA.
months. Alternatively,
the vaccine can be
A Phase III trial is
ongoing in African countries
administered in a
two-dose immunization schedule at
(Mali, Ghana, and
Kenya) and concluded at the
3 and 5 months of age,
followed by a booster
end of 2009.
immunization at 11-12
months of age. It contains
poly- or
oligo-saccharides from seven S. pneumoniae
Lamb-derived monovalent
live attenuated
serotypes (4, 6B, 9V,
14, 18C, 19F and 23F), each
strain, LLR, which is
only being used in China.
conjugated to
genetically detoxified diphtheria toxin
CRM 197. Currently
there are at least the PCV-10 and
Several countries have
introduced the Rotarix
TM
and
PCV-13 being used
mainly in the private sector and in
Rotateq
TM
vaccines into routine
immunization
the high risk
populations in Nigeria.
programmes
*RotaShield
TM
vaccine was introduced
in the USA ,
Haemophilus influenzae type b (Hib) Vaccines
administered in a three
dose schedule but
Infections by Haemophilus influenzae type b are
intussusception noted
within two weeks after
responsible for severe
pneumonia, meningitis and
administration of the
first two doses of vaccine, thus
other invasive diseases
almost exclusively in children
leading to its eventual
withdrawal.
aged less than 5 years.
It is estimated to cause at least 3
million cases of
serious disease every year, and
Streptococcus pneumoniae Vaccine
approximately 386 000
deaths.
Steptococcus pneumoniae: infection is
a leading
Hib
conjugate vaccines :
The Hib
conjugate vaccines
cause of morbidity and
mortality among children
consist of preparations
of polyribosylribitol
worldwide and
particularly in developing countries,
phosphate (PRP) (the
capsular polysaccharide of
estimated that 10.6
million children less than 5 years
Hib) conjugated to a
protein carrier PRP covalently
present with
pneumococcal disease every year. There
bound to a carrier
protein. When conjugated, the
are two types of
vaccines currently licensed for use.
carrier protein induces
a T-cell dependent B-cell
immune response to the
polysaccharide. The Hib
the pneumococcal
polysaccharide vaccine (PPV),
vaccines currently
licensed for use in infants consist
based on purified
capsular PS
of PRPconjugated to a
protein carrier as listed below:
pneumococcal conjugate
vaccines (PCV),
obtained by chemical
conjugation of the
the nontoxic mutant
diphtheria toxin CRM 197
capsular PS to a
protein carrier.
(oligosaccharide
conjugate PRPCRM197),
tetanus toxoid
(PRPT),
23-valent
polysaccharide
vaccine
(PPV23):
The
meningococcal outer
membrane protein
PPV23 vaccine contains
the purified capsular PS
(PRPOMP).
from each of the 23
different S pneumoniae serotypes
that together account
for 90% of cases of severe
The vaccines are
formulated either as single antigens
pneumococcal disease in
industrialized countries.
or as part of
combination vaccines. Hib vaccines are
Two
vaccines
are
currently
manufactured,
safe and efficacious
even when administered in early
Pneumovax 23
TM
(Merck) and Pneumo
23
TM
infancy. Liquid Hib
vaccines are used directly from
(Sanofipasteur).
the vial, whereas
freeze-dried vaccines must be
reconstituted before
administration, either with
A good antibody
response is achieved following a
diluent or with another
vaccine that has been
single IM injection in
60-80% of healthy adults and
specifically identified
and indicated for this purpose
normal children over
two years of age.
PPV23 is
by the manufacturer,
such as DTP.
unable to elicit immune
memory, so that a second
dose of vaccine does
not boost antibody levels. Also,
Malaria Vaccine
PPV23 does not provide
protection against mucosal
infection,
and
is
thus
unable
to
reduce
Approximately 350500
million cases of malaria
nasopharyngeal carriage
of pneumococci. It is poorly
occur annually, killing
between one and three million
immunogenic in less
than 2 years old children and is
people, the majority of
whom are young children in
thus not used in
infants and young children.
sub-Saharan Africa.
Ninety percent of malaria-
related deaths occur in
sub-SaharanAfrica.
193
Malaria vaccines are in
the developmental phase, and
Demonstration of
immunogenicity, efficacy and
there are different
strategies been developed based on
safety in the local
population
the life cycle of the
Plasmodium spp.
Cost effectiveness data
(1 vaccine or
comparisons?)
Pre-erythrocytic
vaccine strategies prevent infection
Inform policy makers,
opinion leaders and
and/or reduce incidence
and severity of disease. Aim
Health Care
Workers
is to generate an
antibody response that will
Inform the community
through proper and
neutralize sporozoites
and prevent them from
sustained engagement
and involvement
invading the
hepatocyte, and/or to elicit a cell-
mediated immune
response that will inhibit intra-
Pay
for its use (GAVI)
hepatic
parasites.
Immunization Systems
Strengthening (ISS)
Asexual blood-stage
(erythrocytic) vaccine strategies
support
performance/reward based system
reduce disease
incidence and severity. Aim is to elicit
New Vaccine Support
(NVS) vaccine provided
antibodies that will
inactivate merozoites and/or
for 1 five years
st
target malarial
antigens expressed on the RBC
Decrease costs of
vaccines (local
surface, thus inducing
antibody-dependent cellular
production)
cytotoxicity and
complement lysis; they also are
Develop easy to use
vaccines (no cold
intended to elicit
T-cell responses that will inhibit the
chain)
development of the
parasite in RBCs : Sexual blood
stage (transmission
blocking) malaria vaccines are
Decrease the number of
dosages
targeting gametocytes,
gametes and/or zygotes. It
Targeted
vaccination
aims to prevent man to
mosquito transmission.
Who to vaccinate?
Importance of
unvaccinated pockets?
Importance of
The RTS, S vaccine is
the first malaria vaccine
differences between
rural and urban?
candidate to
demonstrate that young children and
Large Household
vaccination: Vaccinees
infants exposed to
intense Plasmodium
falciparum
chosen sequentially
from those households
transmission can be
protected from infection and
with the largest number
of susceptibles
malaria disease.
Current malaria
prevention
programs and national
immunization programs need
to be strengthened in
order to be prepared for the
introduction of malaria
vaccines when approved by
regulatory authorities
and recommended as an
Conclusion
additional anti-malaria
tool.
Resources for
introducing new vaccines and
Barriers to Use of Existing Childhood Vaccines
sustaining their use in
developing countries,
including Nigeria are
still comparatively scarce. The
resources will probably
not ever be sufficient to
Lack of disease burden
data
support the use of all
new generation vaccines of
Weak health systems and
its attendant poor
potential public health
utility. Wise use of these funds
logistics such as cold
chain
demands several types
of evidence to inform policy
Poor transportation and
storage systems
decisions. Simplified,
inexpensive and valid methods
Inadequate and poorly
motivated health care
for obtaining crucial
data at the country level, such as
worker
the burden and costs of
disease is needed. There is a
Lack of political
will
need to create an
intellectual framework via research
Barriers to use of “
new ” vaccines
to synthesize diverse
types of relevant evidence to
Poor health
financing
assess the comparative
merits of alternative vaccines
Weak community
participation
and then communicated
to policymakers. To reduce
childhood mortality we
need action now, traditional
Lack of sustainable
partnerships
advocacy methods have
been slow and small in effect.
Improving Vaccine Use in Developing Countries
Advocate its use
Acknowledgement
Generation of local
burden of disease data
(disease surveillance
systems, regional sentinel
Reproduced with kind
permission of the department
sites) which can be
used to create awareness
of Paediatrics and
Child Health of the University of
and sensitized the
population to support the
Ilorin Teaching
Hospital, Iliorin Nigeria owners of
vaccine.
the Ilorin Paediatric
Digest 2010.
194
References
1. Bonnie A, Okonek
M and
3. WHO/UNICEF Review
of
Peters PM
.Vaccines--How
National
Immunization
6. Global Immunization
Data,
and Why?
4. Coverage
1980-2008
October 2009.
2.
WHO
vaccine-preventable
NIGERIA JULY
2009
7. WHO
vaccine-preventable
disease monitoring
system,
5. Global and
regional
diseases monitoring
system
2009 global
summary.
immunization
profile,
2010 global summary
-
African Region,
2009.
country profile
Nigeria.