4.0 Prevention of Infection
Vaccines
Learning Outcomes
National Curriculum Link
SCN 3-13c
SCN 3-20a
HWB 3-15a
HWB 3-16a
Estimated Teaching Time
All students:
 Will discover that vaccines help prevent a range of bacterial and
viral infections
 Will understand that there are not vaccines for all infections
More able students
 Will learn that previously common infections are now rare due to
vaccines
 Will know that most common infections are not prevented by
vaccines
50 minutes
Background Information
Key Words
Antibodies
Antigen
Epidemic
Herd immunity
Immune
Immunisation
Vaccine
White blood cells
Materials Required
Per student
□ Copy of SH 1
□ Copy of SW 1, SW 2,
SW 3
Web Links
www.who.org
Our immune system generally fights any pathogenic microbes that
may enter our bodies. Getting plenty of rest, eating the correct foods
and getting lots of sleep all helps our immune system to work properly
hence preventing infection.
Another means of assisting our immune system is through
vaccinations. Vaccines are used to prevent NOT treat infection. A
vaccine is usually made from weak or inactive versions of the same
microbes that make us ill. In some cases, the vaccines are made from
cells which are similar to, but not exact copies of, the microbe cells
that make us ill.
When the vaccine is injected into the body the immune system attacks
it as if harmful microbes were attacking the body. The white blood
cells create lots of antibodies to attach to the antigens on the
surface of the vaccine cells. Because the vaccine is an extremely
weakened version of the microbe the WBC successfully eliminate all
the vaccine cells and the vaccine will not make you ill. By successfully
eliminating all the cells in the vaccine, the immune system remembers
how to combat those microbes. The next time microbes carrying the
same antigen enter the body the immune system is ready to fight it
before it has a chance to make you ill.
In some cases, the immune system needs reminding and this is why
some vaccinations require booster jabs. Some microbes like the
influenza virus, are tricky and change their antigens. This means that
the immune system is no longer equipped to fight them. For this
reason, we have annual flu vaccinations.
The use of vaccines has meant that a lot of previously common
diseases eg. smallpox have now been eradicated. The re-emergence
of other diseases in a population, e.g. measles, may be due to not
vaccinating a large enough proportion of the population. Epidemics
can be prevented by vaccinating part of the population leading to herd
immunity.
Advance Preparation (10 min)
Copy SH 1, SW 1, SW 2 and SW 3 for each student.
4.0 Prevention of Infection
Vaccines
Introduction (15 min)
1. Begin the lesson by asking students which vaccines/immunisations they have had e.g. polio, MMR, TB
or any holiday vaccinations and if they know what the vaccines were for.
2. Highlight that immune means resistant to disease and that ‘immunisation’ is a way of raising the body’s
immunity to both bacterial and viral disease.
3. Explain that vaccines/immunisations are a harmless small amount of the microbe/disease outer coat
which teaches our body how to fight the bad microbe when or if we get attacked by the disease.
4. Explain how vaccines work (outlined in TS 1) with the help of SH 1. Explain that antibodies pass from
mother to child through breast milk and this helps protect newborn babies from disease.
5. Remind students that microbes can change their outer coats very quickly and that some microbes do
this so quickly that scientists cannot create vaccines for every infection or have to make a new vaccine
every year, like the flu vaccine.
6.
Main Activity (35 min)
1. This activity is best completed in groups of 2 – 3 students.
2. Provide each student with a copy of SH 1 and SW 1, SW 2 and SW 3.
3. Ask the class what they know about the measles? Explain that measles is a highly contagious vaccinepreventable disease caused by the measles virus. Measles is one of the most easily spread diseases
but also the most deadly of all childhood rash/fever illnesses.
4. The World Health Organisation (WHO) examines, records and reports on all health related incidents
across the globe and produces guidelines and recommendations to help prevent infectious disease
epidemics. The incidence of deaths across the world due to measles was so high that in the 1980s
WHO member countries set up national immunisation services in an attempt to eradicate the disease.
5. Tell the class that the table in SW 1 is taken from data collated by WHO, students must manipulate the
data using the equation provided to an incidence per 1000 population. By doing this, students can then
compare the incidence of disease between the European and African regions being examined.
6. Provide the class with SW 2, here the groups should create a bar chart using their data illustrating the
incidence of documented measles cases in both the WHO Europe region and WHO Africa region.
Discuss with the class the trend of measles cases over the years within each region but also between
the two regions. Ask students to highlight the most obvious points / trends.
7. Provide each group with a copy of SW 3, and ask them to answer the questions as a group. When
complete, discuss the answers with the class.
a. In the 1980s, The World Health organisation (WHO) reported an increasing number of
countries establishing national immunisation services with increasing immunisation coverage
in these countries. When do you think these immunisation programmes peaked in the Europe
and Africa regions.
The sharp decline in the incidence of measles cases between 1990 and 2000 suggest that the
immunisation programmes peaked in Europe during the 1990s. In Africa we see 2 cases of
decline, the implementation of programmes in the 1990s caused the initial decline however in
2003 and 2006 the measles vaccine coverage was improved causing the second and third
decline.
b. Can you think on a reason why there are more outbreaks of measles in Africa than in Europe?
The immunisation programme was better implemented and followed in the European region
than in the Africa region with more people becoming vaccinated.
4.0 Prevention of Infection
Vaccines
Main Activity (35 min)
c.
What issues stop the measles vaccine getting to all the people in Africa?
War, poverty, suspicion, lack of health education, lack of government good will and lack of
infrastructure, difficulty delivering the vaccines, and misinformation regarding vaccines all prevent
the vaccines getting to the people who need it.
d. What happens when the measles vaccination drops to a low level within a population?
When the vaccination drops to a low level, people start contracting the disease again leading to a
re-emergence of the disease.
e. Why is vaccination not only a personal health issue but also a public health issue?
Many infectious diseases are extremely contagious, we can vaccinate ourselves against the
disease but other people can contract the disease and spread it further to unvaccinated people. If
more people are vaccinated the disease is prevented from circulating. This is why herd immunity
prevents epidemics. In today’s society where global travel is relatively cheap and easy an infected
person can carry a disease across the world within 24 hours. Herd immunity prevents the
epidemics.
f.
What needs to be done to completely eliminate an infectious disease?
A vaccination programme which reaches all target groups on a wide-spread continual basis is the
only means to completely eliminate a disease. However, it is not possible to eliminate all disease
in this manner as some infectious diseases e.g. avian flu, have other reservoirs outside humans.
g. Why hasn’t the flu vaccine eliminated the influenza virus?
A vaccine works by tricking the body into making antibodies to combat a particular infectious
disease, these antibodies then attach themselves to the antigens in the outer coat of the virus.
The influenza virus however mutates and changes its outer coat faster than scientists can create
appropriate vaccines.
h. Why is a vaccine regarded as a preventative measure and not a treatment?
Vaccines are used to boost the body’s immunity so that when an infectious disease does enter the
body, the immune system is ready to fight it preventing the establishment of disease.
Extension Activity
1. Provide the class with a copy of SW 3.
2. Each student should look examine the world map provided and highlight on the map which vaccines
are required to visit which countries. Students should also name the disease the vaccine protects
against and the microbe that causes this disease. Information can be found at www.who.org,
www.traveldoctor.co.uk or by visiting their local medical centre.
Teacher Answer Sheet 1
Using the data in SW 1 complete the following table and graph:
Number of reported cases of measles per 1000
Year
100
Title
1990
Europe
449.5
Africa
942.1
2000
41.7
775.2
2002
51.8
406.2
2003
31.1
558.5
2004
32.4
469.3
2005
40.9
416.9
2006
57.6
127.8
Reported incidence of measles per 1000 population for WHO Europe and Africa
90
In order for other
people to be able to
read your results, it is
important that the
graph has a title that
describes the graph
contents and that the
X and Y axis are
labelled
appropriately.
Reported cases of measles per 1000 population
80
70
60
50
40
LABEL
30
Legend
20
Africa Region
Europe Region
10
0
1990
2000
LABEL
2002
2003
Year
2004
2005
2006
Fact Sheet
The immune
system is our main
defence against any
pathogenic microbes.
Exercise, rest and
a balanced diet all help
our immune system
work properly and
prevent
infection.
Vaccinations can also help
our immune system. They
are used
to prevent NOT treat infection
by stimulating the immune
system to recognise and
destroy the disease causing
microbe. Vaccines are a
weak or inactive version
of the pathogenic microbe.
The immune system
attacks the vaccine thinking
it is a harmful microbe. The white
blood cells create lots of antibodies
which attach to the antigens on the
surface of the vaccine cells. The
antibodies destroy all the vaccine cells
before it can make you ill. The
antibodies then stay in the blood
stream for many years, waiting to
attack and destroy the real
pathogenic microbes if they
ever enter the body.
Some microbes like
the flu, are tricky and
change their antigens.
This means that the
immune system can’t
remember how to fight
them. For this reason,
We have annual flu
vaccinations.
The use of vaccines has meant
that a lot of previously common
diseases eg. Smallpox have now been
eliminated. While a vaccine protects an
individual an infectious disease will only be
eradicated if vaccines are used on a
wide-spread population wide basis. This is
known as herd immunity. Epidemics can be
prevented by herd immunity.
The data below details the population and reported cases of measles in the regions Europe and Africa, as recognised by the World Health Organisation. This
information is usually documented as reported cases per 1000 population for comparison purposes. In the third column, calculate the number of reported cases
per 1000 population using the following equation: B / (A / 1000) where A = population in thousands and B = reported measles cases.
WHO Europe Region
Population in
thousands
Year
1990
522 443
Reported
measles
cases
234 827
2000
895 997
37 421
2002
901 440
46 714
2003
904 883
28 199
2004
908 411
29 503
2005
911 776
37 332
2006
915 553
Population in
thousands
Reported cases/1000
population
52 765
WHO Africa Region
Year
1990
510 853
Reported
measles
cases
481 204
2000
670 918
520 102
2002
705 094
286 380
2003
722 580
403 572
2004
740 358
220 732
2005
758 439
316 224
2006
776 830
99 339
Reported cases/1000
population
Using the data in SW 1 complete the following table and graph:
Number of reported cases of measles per 1000
Year
Europe
Africa
1990
2000
2002
2003
2004
2005
2006
Title
100
90
In order for other
people to be able to
read your results, it is
important that the
graph has a title
explaining what you
are trying to show
and that the X and Y
axis are labelled
appropriately.
80
70
60
50
40
30
LABEL
Legend
20
10
0 1990
2000
LABEL
2002
200
3
2004
2005
2006
Conclusions
1. In the 1980’s the World Health Organisation (WHO) reported an increasing number of
countries establishing national immunisation services with increasing immunisation coverage
in these countries. When do you think these immunisation programmes peaked in the
Europe and Africa regions. Provide a reason for your answer.
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
2. Can you think on a reason why there are more outbreaks of measles in Africa than in
Europe?
_________________________________________________________________________
_________________________________________________________________________
3. What issues stop the measles vaccine getting to all the people in Africa?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
4. What happens when the measles vaccination drops to a low level within the population?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
5. Why is vaccination not only a personal health issue but also a public health issue?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
6. What needs to be done to completely eliminate an infectious disease?
_________________________________________________________________________
_________________________________________________________________________
7. Why hasn’t the flu vaccine eliminated the influenza virus?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
8. Why is a vaccine regarded as a preventative measure and not a treatment?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
In the boxes provided, compile a list of vaccines required, if any, to visit each of the regions on the map.
Canada:
Western Europe:
Russia:
Far East:
Asia:
S. America:
Africa:
Australia: