Immunization Module: Antibacterial Vaccines

Study Session 2  Antibacterial Vaccines

Introduction

You learned about the main vaccine-preventable bacterial diseases in Study Session 3 of the Communicable Diseases Module, Part

The most effective way of reducing the major vaccine-preventable diseases is to maintain a high level of immunization in the whole population, using the routine Expanded Programme on Immunization (EPI) vaccines. In this study session, you will learn about the antibacterial vaccines that are approved for routine use in Ethiopia for preventing some common bacterial diseases, and the storage, dosages and schedules for immunization with these vaccines.

Figure 2.1  Immunization saves millions of children’s lives. (Photo: AMREF Ethiopia/Demissew Bizuwork)

This study session will also help you to give clear information about vaccination to the people in your community, including the importance of giving the vaccines as scheduled to their children – even though it makes them cry for a short time (Figure 2.1). Reassure parents about the low risk of adverse events following immunization (AEFIs) and how to manage vaccine reactions if they occur.

As you learned in Study Session 1, contraindication — in the context of immunization — means a medical reason for not giving the vaccine, either temporarily or permanently. Note that children with a mild illness should still be immunized at the scheduled time. Contraindications, such as a high-grade fever (38.5^oC or above), mean you should refer the child to a health centre and wait until they recover before giving the missed vaccine dose. Specific contraindications for each vaccine are given in the sections that follow.

Learning Outcomes for Study Session 2

When you have studied this session, you should be able to:

• 2.1  Define and use correctly all of the key words printed in bold. (SAQs 2.1 and 2.5)
• 2.2  Describe the antibacterial vaccines included in the Expanded Programme on Immunization (EPI) in Ethiopia. (SAQs 2.1, 2.2 and 2.4)
• 2.3  Describe the storage, dosages and schedules of the antibacterial EPI vaccines. (SAQs 2.1 and 2.2)
• 2.4  Describe the possible adverse events following immunization with the antibacterial EPI vaccines and how you manage them at Health Post level. (SAQs 2.3 and 2.4)
• 2.5  Describe the contraindications that mean you should not immunize a child with one of the antibacterial EPI vaccines. (SAQs 2.3 and 2.5)

2.1  BCG vaccine

2.1.1  What is BCG?

Tuberculosis diagnosis and treatment is fully described in Study Sessions 13 to 17 in the Communicable Diseases Module, Part 2.

You have already learned about the different types of vaccines in Study Session 1. BCG is a live-attenuated antibacterial vaccine that protects against severe forms of tuberculosis in infants and young children. Tuberculosis (TB) is a disease caused by the bacterium Mycobacterium tuberculosis. It usually attacks the lungs, but can also affect other parts of the body, including the bones, joints and brain. The letters, B, C and G stand for Bacillus of Calmette and Guerin.

Bacillus describes the rod shape of the tuberculosis bacteria; Calmette and Guerin are the names of the people who developed the vaccine.

2.1.2  Effectiveness of BCG vaccine

The effectiveness of a vaccine means its capability to protect vaccinated people from the disease that immunization aims to prevent. In the case of BCG vaccine, the effectiveness is highly variable — protection from TB ranges from 0–80% of those who are vaccinated. This means that some vaccinated individuals may not be protected against TB at all, and up to 80% of the others will receive some protection. The strongest reason for vaccinating with BCG is that it protects young children against developing the more serious forms of tuberculosis, such as TB meningitis (affecting the brain), TB in both lungs and extra-pulmonary TB (affecting other organs).

2.1.3  BCG vaccine storage, dosage and immunization schedule

BCG vaccine is a freeze-dried powder, supplied in small glass bottles called ampoules. Vaccines that come as powders must be mixed with a liquid called a diluent. This process is known as reconstitution, which means thoroughly mixing the powder with the diluent to activate the vaccine before it can be administered. Before use, you must reconstitute BCG vaccine powder with the appropriate diluent supplied for this purpose, using a mixing syringe to mix the diluent with the powder in the ampoule. You will learn how to do this in Study Session 4.

2.1.4  Adverse events following BCG immunization and how to treat them

Adverse events may occasionally occur after immunization, in addition to the desired protective effect. They can include swelling and tenderness at the injection site. For BCG immunization, the normal reaction is a small raised swelling, which immediately appears at the injection site (Figure 2.2 on the next page). This usually disappears within 30 minutes.

Figure 2.2  A small raised swelling can be seen at the site of an intradermal BCG injection. (Photo: AMREF Ethiopia/Demissew Bizuwork)

After approximately two weeks, a small red sore normally develops at the injection site, which is about 10 mm in diameter (the size of the unsharpened end of a pencil). The sore remains for about another two weeks and then heals, leaving a small scar about 5 mm across (Figure 2.3). This is a sign that the child has been effectively immunized. If there is no scar at the injection site six weeks after a BCG immunization, the injection must be repeated. If there is still no skin reaction to the second injection, the child should be referred to a higher-level health facility.

Figure 2.3  (a) The small sore at the injection site is a sign that the child has been effectively immunized with BCG vaccine. (b) A healed BCG vaccination scar on the arm of an adult. (Photos: supplied by Dr Kalid Asrat and Dr Basiro Davey)

Occasionally, there is an abnormal adverse event following BCG immunization, such as swelling of glands in the armpit, or rarely the formation of an abscess at the injection site (Figure 2.4).

An abscess is a collection of pus and inflamed tissue at the site of bacterial infection. It can be due to bacterial causes other than BCG.

Figure 2.4  An abscess is a rare adverse event following BCG immunization. This one is about 1.5 cm in diameter, but they can be larger. (Photo: supplied by Dr Kalid Asrat)

Abnormal adverse events following BCG vaccination may occur because:

• an unsterile needle or syringe was used
• too much vaccine was injected
• the vaccine was injected too deeply under the skin, instead of into its top layer.

Table 2.2 summarises the adverse events that may occur following BCG immunization and how you can treat them at Health Post level.

2.1.5  Who should not get BCG vaccine?

The only contraindications for BCG immunization are symptoms of HIV infection. These include chronic lung infection, tuberculosis, persistent diarrhoea and other serious symptoms of HIV-related diseases, as described in the Communicable Diseases Module, Part 3.

2.2  Pentavalent vaccine

2.2.1  What is pentavalent vaccine?

A vaccine that contains five different antigens in one combined preparation is called a pentavalent vaccine (‘penta’ comes from the Greek word for five). You do not need to remember these details, but the pentavalent vaccine in common use in Ethiopia is a combination of one inactivated whole-cell vaccine (against pertussis bacteria), two sub-unit vaccines (the diphtheria and tetanus toxoids), one conjugate vaccine (against Haemophilus influenza type b bacteria) and one recombinant vaccine (against hepatitis B virus). Thus, the pentavalent vaccine used in Ethiopia in the EPI combines five different vaccines in one injection to protect against four bacterial diseases: diphtheria, tetanus, pertussis and Haemophilus influenzae type b (often abbreviated to Hib), and one viral disease caused by hepatitis B viruses. It is a fully liquid vaccine, which comes in a single dose vial.

Sometimes you will see the pentavalent vaccine used in Ethiopia described as DPT-HepB-Hib vaccine. This is the term used in the IMNCI Module in this curriculum.

2.2.2  The anti-bacterial components of pentavalent vaccine

Three of the antibacterial components in the pentavalent vaccine used routinely in the EPI in Ethiopia are known as DPT (diphtheria-pertussis-tetanus), referring to the three bacterial diseases they prevent. In Ethiopia, DPT is only given in the pentavalent vaccine, but some other countries give DPT as a separate injection. The fourth antibacterial component of the Ethiopian pentavalent vaccine is called Hib, which stands for Haemophilus influenzae type b. These four components are described below.

2.2.3  Storage, dosage and schedule of pentavalent vaccine

Pentavalent vaccine comes in single-dose glass bottles called vials, which should be stored at between +2°C and +8°C. It should never be frozen, or allowed to become warmer than +8°C, as this will destroy its effectiveness.

If it is allowed to stand for a long time, fine particles settle to the bottom of the vial leaving a cloudy liquid above them. This is normal. Shake the vial to mix the vaccine with the liquid before using it.

Three doses of 0.5 ml each are given intramuscularly (IM, into the muscle) of the upper outer part of the left thigh, before injecting pneumococcal vaccine (PCV10) in the right thigh (see Section 2.3.1). The injections are given to infants at the age of 6, 10 and 14 weeks. If an infant misses a scheduled dose, give it as soon as possible and complete the series of three doses — there is no need to start the series of doses over again. Pentavalent vaccine is usually not given after 6 years of age because there is an increased risk of adverse reactions in older children.

The characteristics of immunization with pentavalent vaccine are summarised in Table 2.3.

2.2.4  Effectiveness of pentavalent vaccine

On average, 78–95% of individuals who have received three vaccine doses will normally be protected against all five diseases covered by the pentavalent vaccine. This means that in every 100 people who receive three doses, on average, between 78–95 of these individuals will be protected against all five diseases.

2.2.5  Adverse events following pentavalent immunization and how to treat them

The possible adverse events following immunization with pentavalent vaccine are generally mild: serious reactions are very rare (see Section 2.2.6). The mild reactions are:

• Soreness. Some children may develop mild soreness, redness, or swelling at the injection site, but this will go away within 1–3 days.
• Fever. Some children may develop a mild fever (a temperature of around 37.3^oC to 38.4^oC, measured with a thermometer in the child’s armpit, is termed a low-grade fever). It should disappear within a day. Fever that begins more than 24 hours after a pentavalent injection is unlikely to be a reaction to the vaccine and should be investigated.
• Crying for more than three hours, mostly because of pain, occurs in up to 1% of infants.

A serious but rare adverse event is an abscess, which may develop a week or more after immunization (Figure 2.5), usually because an unsterile needle or syringe was used, or the vaccine was not correctly injected into the muscle. The management of these adverse events at Health Post level is summarised in Table 2.4.

Figure 2.5  An abscess caused by an unsterile needle or syringe, or incorrectly administered pentavalent vaccination. (Source: WHO, 1998, Immunization in Practice, Module 2, EPI Vaccines, Figure 2-C, p.8)

2.2.6  Who should not get pentavalent vaccine?

A child who develops a severe reaction to the first vaccination should be referred to a higher level health facility immediately.

Do not give another dose of the pentavalent vaccine if a child develops any of these severe reactions to the first dose:

• Severe allergic reaction (doctors call it anaphylaxis), which includes severe rash, breathing difficulty, signs of shock, weak and rapid pulse, dizziness or fainting.
• Encephalopathy, (Enchephalopathy is pronounced ‘en-seff-ah-lopp-ah-thee’) which is a disease of the brain that presents with coma, decreased level of consciousness and/or prolonged convulsions, occuring within seven days of a pentavalent vaccination, and where the symptoms are not due to another identifiable cause.

2.3  Pneumococcal vaccine (PCV10)

Next we describe a new antibacterial vaccine that is being introduced into the routine EPI in Ethiopia.

Pneumococcal infections are described in the Communicable Diseases Module, Part 4, Study Session 35.

Pneumococcal vaccines (PCVs) protect against pneumonia and other pneumococcal infections caused by Streptococcus pneumoniae bacteria. These bacteria can attack different parts of the body, causing serious infections in the lungs (pneumonia), the inner ear (acute otitis media), the bloodstream (bacteraemia), and the membranes covering the brain and spinal cord (meningitis). The WHO estimates that up to one million children die of pneumococcal infections every year, mainly in sub-Saharan Africa and South East Asia. In Ethiopia, pneumonia is the leading cause of death among children under five years, accounting for 28% of all deaths in this age group.

The Streptococcus pneumoniae bacteria exist in many different ‘strains’. Several different conjugate pneumococcal vaccines have been developed to give protection against different subsets of these strains. The vaccine that is being introduced in Ethiopia as part of the EPI is called PCV10, also known by its brand name Synflorix. PCV10 is highly effective at preventing infections caused by the strains of Streptococcus pneumoniae bacteria included in the vaccine preparation.

2.3.1  Storage, dosage and schedule of PCV10

PCV10 is a freeze-sensitive vaccine, which must be stored in the refrigerator between +2^oC to +8^oC. You should keep the vials on the same shelf of the refrigerator as the vials of pentavalent vaccine because they are given to infants at the same immunization session. The liquid PCV10 does not contain any preservative, so once you have opened a vial, any unused vaccine should be discarded after six hours and not returned to the refrigerator.

The vaccination schedule for PCV10 (Synflorix) is the same as for the pentavalent vaccine: three doses are given at 6, 10 and 14 weeks of age by intramuscular (IM) injection into the right outer upper thigh muscle (the opposite thigh to the pentavalent vaccine). The dosage for each vaccination with PCV10 is 0.5 ml. The vaccine is a liquid that comes in two-dose vials.

Any child who presents to a health facility for vaccination who is aged less than one year old is eligible to receive PCV10 vaccine if they missed the primary series of doses at 6, 10 and 14 weeks. Children should receive all three doses of PCV10 by their first birthday, but if a child starts their first dose of PCV10 at the age of 11 months, they should complete the remaining two doses at intervals of four weeks. Table 2.5 (on the next page) shows the schedule for PCV10 immunizations for children who have already started the series of pentavalent vaccine doses.

2.3.2  Adverse events and contraindications of PCV10

Refer all cases of severe vaccine reactions urgently.

Mild local reactions (redness, pain and slight swelling at the injection site) and/or mild fever and irritability of the child may occur in one-third to one-half of the infants vaccinated with PCV10, but these reactions usually disappear within 24 hours. Manage these mild reactions as described earlier in Table 2.4 for pentavalent vaccine. Rare severe reactions to the vaccine include convulsions, severe allergic reaction (anaphylaxis), swollen lymph glands and encephalitis.

The contraindications for PCV10 are the same as for pentavalent vaccine: do not give PCV10 to an infant who comes to you with a high-grade fever, or who developed a severe vaccine reaction after a previous dose. However, you should vaccinate infants with PCV10 if they only have a mild illness, such as a common cold or low-grade fever.

2.4  Tetanus toxoid (TT) vaccine

2.4.1  What is tetanus toxoid vaccine?

The same tetanus toxoid (TT) vaccine that is given to infants in the pentavalent vaccine is also given on its own, as a single vaccine, to women of childbearing age (Figure 2.6). The vaccine is a cloudy liquid, and the powder can settle to the bottom of the vial if it is left to stand for a long time. Shake the vial to mix the vaccine powder and liquid before use.

Figure 2.6  These women are of childbearing age and should be immunized with TT vaccine to protect them and their babies from tetanus. (Photo: AMREF Ethiopia)

2.4.2  Schedule, dosage, storage and effectiveness of TT vaccine

If given as a separate vaccine to pregnant and non-pregnant women of childbearing age, at least two doses of 0.5 ml of TT vaccine are given intramuscularly (IM) into the upper arm (Figure 2.7); but for maximum long-lasting protection throughout the childbearing years women should receive more than two doses (TT2+), and the ideal is to give five doses. It should be stored at between +2^oC and +8^oC and never frozen. Table 2.6 summarises the characteristics of TT vaccine; the periods of protection after each dose are given in Table 2.7.

Figure 2.7  Make sure all pregnant women are immunized against tetanus.

2.4.3  Adverse events and contraindications of TT vaccine

The possible adverse events following immunization of women with TT vaccine are usually mild: low-grade fever, and soreness/pain at the injection site (see Table 2.6 above), which can be treated with paracetamol in women who are not already pregnant. Women of child-bearing age who developed a severe allergic reaction or encephalopathy to a previous dose of TT vaccine should not be given TT again.

2.5  Meningococcal vaccines

Finally, we refer to the meningococcal vaccines which are in common use in some countries. Although not yet routinely available in the EPI in Ethiopia, these vaccines are used to control outbreaks of meningitis caused by the Neisseria meningitides bacteria, which occur in at least six different types. Types A, B, C, Y, W135 and X cause most cases of meningococcal meningitis. Quadrivalent vaccines (containing the antigens of four of these types) are available in the USA, and a vaccine specifically designed for Africa is being used in the countries with the highest burden of meningococcal meningitis.

2.6  In conclusion

Table 2.8 summarises the antibacterial vaccines in the Expanded Programme on Immunization (EPI) in Ethiopia. In Study Session 3, we will turn our attention to the antiviral vaccines in the EPI.

Summary of Study Session 2

In Study Session 2, you have learned that:

1. The most effective way to protect people from the common vaccine-preventable diseases is to maintain a high level of immunization with the vaccines in the routine Expanded Programme on Immunization (EPI).
2. The common EPI antibacterial vaccines used in Ethiopia are: BCG, which protects children against the most serious effects of tuberculosis (TB); a pentavalent vaccine, which protects against diphtheria, pertussis, tetanus, cases of meningitis and pneumonia caused by Haemophilus influenzae type b, and hepatitis B liver disease; and PCV10, which protects against pneumonia and some other infections caused by specific strains of Streptococcus pneumoniae bacteria.
3. At least two doses of TT vaccine (and ideally five) should also be given to pregnant women and women of childbearing age to protect them and their newborns from tetanus.
4. A meningococcal vaccine is available to control outbreaks of meningitis caused by Neisseria meningitides bacteria; it is not a routine EPI vaccine.
5. To guarantee long-term protection, all doses of the routine antibacterial vaccines in the EPI should be given. A child who misses a vaccination should be given the missed dose as soon as possible and complete any remaining doses at the scheduled time.
6. The EPI antibacterial vaccines are very effective and safe for infants, and TT vaccine is safe for women of childbearing age and during pregnancy. Adverse events following immunization are usually mild, e.g. low-grade fever and soreness at the injection site, which can easily be managed; serious adverse events are extremely rare.
7. Infants with minor illnesses may be immunized safely. But if they are suffering from a high fever (38.5^oC or above), they should be referred to a health centre; delay the immunization until after they recover. Other contraindications are HIV disease, severe allergic reaction or encephalopathy following a previous dose of a vaccine.

Self-Assessment Questions (SAQs) for Study Session 2

Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering these questions. Write your answers in your Study Diary and discuss them with your Tutor at the next Study Support Meeting. You can check your answers with the Notes on the Self-Assessment Questions at the end of this Module.