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AS LONG AGO AS 429 BC, THE GREEK HISTORIAN THUCYDIDES OBSERVED THAT THOSE WHO SURVIVED THE SMALLPOX PLAGUE IN ATHENS DID NOT BECOME RE-INFECTED WITH THE DISEASE.
AS LONG AGO AS 429 BC, THE GREEK HISTORIAN THUCYDIDES OBSERVED THAT THOSE WHO SURVIVED THE SMALLPOX PLAGUE IN ATHENS DID NOT BECOME RE-INFECTED WITH THE DISEASE.

Childhood Immunisation – The safest and most effective way to protect individuals and communities from infectious diseases

Introduction:

After clean water, vaccination is the most effective public health intervention in the world for saving lives and promoting good health.1 Effective immunisation has made a major contribution to reducing the incidence of many infectious diseases and in eradicating naturally occurring smallpox. It is hoped that poliomyelitis (polio) will also be eradicated soon.

The term vaccination originated from the procedure used to protect people with the first vaccine for smallpox, vaccinia. The terms of ‘vaccination’ and ‘immunisation’ are commonly used interchangeably with similar meaning. However, vaccination is now used to refer to all procedures for immunisation. Immunisation is the process of protecting individuals from infection through passive or active immunity.1

Passive immunity is provided by administering antibodies, such as varicella zoster immune globulin (VZIG) for preventing chickenpox in pregnant women. Active immunity is achieved through stimulating the individual’s immune system by a vaccine.

Most of the currently available vaccines are administered through needle injections. Some vaccines such the Oral Polio and Typhoid have been given by mouth and others such the new live attenuated influenza vaccine is administered by intranasal route as an aerosol. 2

The history of vaccination:

Vaccination is a miracle of modern medicine. In the past 50 years, it’s saved more lives worldwide than any other medical product or procedure. But the fascinating story of vaccination goes back all the way to ancient Greece.11

As long ago as 429 BC, the Greek historian Thucydides observed that those who survived the smallpox plague in Athens did not become re-infected with the disease.

In 900AD; the Chinese discover and use a primitive form of vaccination called variolation. It was carried out as early as the 10th century, and particularly between the 14th and 17th centuries. The aim was to prevent smallpox by exposing healthy people to tissue from the scabs caused by the disease. They did this by either putting it under the skin or, more often, inserting powdered scabs from smallpox pustules up the nose.

In 1700s: Variolation spreads around the world. It eventually spread to Turkey, and arrived in England in the early 18th century. At this time, smallpox was the most infectious disease in Europe. It struck rich and poor, and killed up to one-fifth of those infected in numerous epidemics. Variolation caused mild illness but, although it occasionally caused death, smallpox rates were lower in populations that tried it.

In 1796 a British physician, Dr Edward Jenner (pictured above), discovered vaccination in its modern form and proved to the scientific community that it worked.

History of vaccine development and introduction of vaccines into the UK immunisation programmes is illustrated here.

In 2008 human papillomavirus (HPV) vaccination, known as cancer vaccine, was introduced into the routine childhood immunisation schedule for girls.

Childhood immunisation schedules:

Different countries in the world follow slightly different national immunisation schedules. Common vaccine preventable diseases covered by these schedules are: Diphtheria, Pertussis (Whooping Cough), Tetanus, Poliomyelitis, Haemophilius influenzae Type B, Measles, Mumps, Rubella and Meningitis. Some other vaccines such BCG, Hepatitis B, Rotavirus, Human Papilloma Virus (HPV) and Yellow Fever are part of routine national immunisation schedules in some countries but not in others. Depending on the availability and affordability, many countries use the Measles, Mumps and Rubella combined vaccine (MMR) while others use single antigen vaccines for these conditions.  There is also some minor difference in the timing of starting dose and subsequent schedules worldwide. Up to date details for each country can be found on the following WHO website:http://apps.who.int/immunization_monitoring/en/globalsummary/scheduleselect.cfm

Table I (below) is the current UK national childhood immunisations schedule:

Table 1: Routine Childhood Immunisation Schedule – UK

When to immunise What is given Vaccine and how it is given
Two months old Diphtheria, tetanus, pertussis, polio and Haemophilus influenzae type b (DTaP/IPV/Hib) One injection (Pediacel)
Pneumococcal (PCV) One injection (Prevenar)
Three months old Diphtheria, tetanus, pertussis, polio and Haemophilus influenzae type b (DTaP/IPV/Hib) One injection (Pediacel)
Meningitis C (MenC) One injection (Neisvac C or Meningitec or Menjugate)
Four months old Diphtheria, tetanus, pertussis, polio and Haemophilus influenzae type b (DTaP/IPV/Hib) One injection (Pediacel)
Pneumococcal (PCV) One injection (Prevenar)
Meningitis C (MenC) One injection (Neisvac C or Meningitec or Menjugate)
Between 12 and 13 months old – within a month of the first birthday Haemophilus influenzae type b, Meningitis C (Hib/MenC) One injection (Menitorix)
Measles, mumps and rubella (MMR) One injection (Priorix or MMRvaxPro)
Pneumococcal (PCV) One injection (Prevenar)
Three years four months to five years old Diphtheria, tetanus, pertussis and polio (dTaP/IPV or DTaP/IPV) One injection (Repevax or Infanrix-IPV)
Measles, mumps and rubella (MMR) One injection (Priorix or MMRvaxPro)
Girls aged 12-13 years Human Papillomavirus Vaccine (HPV) 3 injections as per schedule of 0,1 and  4-6 months (Gardasil).
Thirteen to 18 years old Tetanus, diphtheria and polio (Td/IPV) One injection (Revaxis)

 

Individuals who fall into certain risk groups may be offered extra vaccines. These include vaccinations against diseases such as hepatitis Btuberculosis (TB),  flu and chickenpox. There are also optional vaccines such as hepatitis A, yellow fever,typhoid and cholera for people traveling to at risk countries.

Further up to date details on travel vaccines can be checked on the UK NHS Travel vaccines website at:http://www.nhs.uk/Planners/vaccinations/Pages/Travelvaccines.aspx

Vaccine Types:

Generally, there are two types of vaccines: Live attenuated vaccines such as measles, mumps and rubella (MMR); yellow fever; oral polio (OPV) and BCG. Inactivated vaccines such as such as pertussis and inactivated poliomyelitis virus (IPV). Other non-live vaccines contain only the antigens that are important for protection. For example, tetanus and diphtheria vaccines contain inactivated toxins (toxoids), influenza vaccine contains a surface protein called haemagglutinin, and pneumococcal vaccine contains the polysaccharide from the capsule. DNA vaccines being tested in humans include those against the viruses that cause influenza and herpes. Researchers are also working on both bacterial and viral-based recombinant vector vaccines for HIV, rabies, and measles.3

Live attenuated vaccines produce longer lasting immunity, similar but less than that produced by natural infection. Often one dose confirms long lasting immunity, but they are inherently less stable than killed vaccines and with the possibility of reversion to wild strain, as in polio. Some may spread, enhancing herd-immunity but putting at risk individuals with weaker immune system. There is at least 4 weeks interval required between administering 2 different live vaccines if not administered at the same in the same individual. 2

Inactivated vaccines, on the other hand, usually require a series of primary vaccinations followed by boosters. Some of these vaccines have adjuvants (for example aluminium hydroxide, aluminium phosphate) to enhance the antibody response. There is no risk of person-to-person spread, and the vaccines are more stable. There is usually no need for observing an interval between administering of two or more non-live vaccines if not administered at the same time. There is also no need for observing an interval between live and no-live vaccines if not given at the same time.

The importance of Childhood Immunisation:

Newborn babies are immune to many diseases because they have antibodies they got from their mothers. However, this immunity weans during the first year of life. Moreover, these young children do not have this “maternal immunity” against some diseases, such as whooping cough. 4 When unvaccinated child is exposed to a disease germ, the child’s body may not be strong enough to fight the disease. Before vaccines, many children died from diseases that vaccines now prevent, such as whooping cough, measles, and polio.

Immunising individual children also helps to protect the health of our community (herd immunity), especially those people who cannot be immunised such as those who are too young to be vaccinated, those who cannot be vaccinated for medical reasons (for example, children with leukaemia), and those who cannot make an adequate response to vaccination (especially those children with weaker immune system).

Many childhood diseases which cause significant morbidity and mortality can now be prevented by vaccines that have high efficacy and are considered safe, in that their side effects have an acceptably low incidence and severity. In combination with improvements in hygiene and nutrition, public vaccination programmes have saved millions of children from suffering and death.

Table 2 compares the reduction of mortality and the incidence of some vaccine preventable disease in the UK prior to the introduction and after establishment for several decades (1996) of the specific vaccination programmes against the vaccine preventable disease.

  Table 2:
Disease  Cases p.a. Deaths p.a
Last year before immunisation started 1996 Last year before immunisation started 1996
Diphtheria 47,061 2,133 12 0
Tetanus 32 8 0
Pertussis 92,410 92 2,387 2
HI meningitis  417 22 38 0
Measles 460,407 99 5,613 0

Immunisation currently averts an estimated 2 to 3 million deaths in the world every year in all age groups from diphtheria, tetanus, pertussis (whooping cough), and measles. 5 In the UK; prior to the introduction of the diphtheria vaccine in 1939, around 45,000 notifications were recorded annually in the UK, with over 2,000 deaths. In 1957, only 37 notifications were recorded with six deaths.6

Figure 1 shows a drastic reduction in diphtheria cases and mortality in the UK after starting the Diphtheria vaccination programme as another example of vaccination success.

Immunisation coverage

Despite all the efforts of the world community, 1.5 to 2 million children still die every year from vaccine-preventable diseases.5 Immunisation coverage is levelling off in many countries and falling in others. In the UK, there appears to be a worrying trend of a decrease in vaccination coverage (particularly for MMR). UK figures for immunisation coverage for children aged one, two and five years are compiled quarterly.

The percentages of children immunised by their second birthday are given in this table

The dangers posed by falling immunisation coverage are real. For example, in 1974, Japan had a reasonably successful pertussis vaccination programme in which nearly 80 per cent of children were vaccinated. There were only 393 cases of whooping cough that year, and no deaths. In 1975, pertussis immunisation in Japan was suspended for two months following the deaths of two children who died within 24 hours of receiving the vaccine, although it was later found that their deaths were not caused by vaccination. Rumours that the vaccine was unsafe meant that by 1976, coverage for two year olds had dropped as low as 10 per cent. In 1979 Japan suffered a major pertussis epidemic with more than 13,000 cases and 41 deaths. In 1981 the government began vaccinating with acellular pertussis vaccine, and the number of pertussis cases dropped again.7

As demonstrated in the screen snapshot below from the of the UK immunisation Green Book; a similar situation occurred in the UK following publication of a paper in 1974 that suggested a link between the pertussis vaccine and encephalopathy causing serious conditions of the nervous system, such as epilepsy and learning disorders. This led to a fall in the number of children immunised and hence an increase in cases. There were about 100,000 extra cases of whooping cough between 1977 and 1980.8

Contraindications to immunisations

There will be very few individuals who cannot receive vaccines. Where there is doubt, appropriate advice should be sought from a consultant paediatrician, immunisation co-ordinator or consultant in communicable diseases control rather than withholding vaccine.2 The risk of individual of not being immunised must be taken into account.

As far general contraindications are concerned, al vaccines are contraindicated in those who have had: 2

  • a confirmed anaphylactic reaction to a previous dose of a vaccine containing the same antigens, or
  • a confirmed anaphylactic reaction to another component contained in the relevant vaccine, e.g. neomycin, streptomycin or polymyxin B (which may be present in trace amounts in some vaccines).

Live vaccines may be temporarily contraindicated in individuals who are: 2

  • immunosuppressed
  • pregnant

There is also a long list of conditions that usually require postponing the administration of vaccine rather than contra indicating. For example, a child is acutely ill, running high temperature, receiving immunosuppressing treatment (in the case of live vaccine) and those with progressive neurological conditions at the time of vaccine administration.

Vaccine safety:

Vaccination is very safe and effective(http://immunisation.dh.gov.uk/). Vaccines are licensed for public use after several stages of initial clinical trials by testing its safety, efficacy and acceptability by the target population. In the UK; vaccines are recommended to the government on the advice of the Joint Committee on vaccination and Immunisation (JCVI). Vaccine use is licensed and monitored by the Medicines and Healthcare products Regulatory Agency (MHRA), with safety checks carried out by the National Institute for Biological Standards and Control (NIBSC), the UK’s official medicines control laboratory.

Vaccines therefore are only given to children after a long and careful review by scientists, doctors, and healthcare professionals. Though vaccines commonly cause some discomfort and pain, redness, or tenderness at the site of injection this is minimal compared to the pain, discomfort, and trauma of the diseases these vaccines prevent. As mentioned before, serious side effects following vaccination, such as severe allergic reaction, are very rare. The disease-prevention benefits of getting vaccines are therefore much greater than the possible side effects of a vaccine.

The risks of vaccine-preventable disease versus risks of vaccine can be noted in the table 3 below for the Measles disease and the MMR vaccine as an example.

Table 3: Risks of the disease versus risks of the vaccine
Measles MMR Vaccine
All get rash and fever1 in 20 get ear infections, diarrhoea6 in 100 get pneumonia18 in 100 are hospitalised1 in 1,000 get encephalitis2 in 1,000 will die from it5-10 in a million get subacute Sclerosing panencephalitis (SSPE) 5% get rash or 5-15% fever at 7-12Days lasting 1-2 days1 in 2,000 get ear infections1 in 1,000 are hospitalised1 in 3,000 are hospitalised with a Febrile convulsion<1 in 1,000,000 get encephalopathyJoint symptoms 25% (adult women)Thrombocytopenia <1 in 30,000 doses

Source: Joint Committee on Health and Children (2001) Report on childhood immunisation. Parliament of Ireland.

(www.irlgov.ie/committees-01/c-health/rep-childhood/default.htm)

Herd immunity:

Her immunity also known as population immunity is the state achieved when immunisation programmes reach sufficiently high coverage of the target population to interrupt transmission within the community). Both immunised and non-immunised individuals then benefit. Herd immunity is one of the factors taken into account in all national immunisation programmes.6

The percentage of the population that must be immunised for population immunity to be created depends on several factors including the infectivity of the disease , the susceptibility and vulnerability of the population, environmental factors (for example, reservoirs of the organism) and the efficacy of the vaccine.

Table 4: Efficacy of vaccines                                                                                     
Vaccine Vaccine Efficacy (%)
Diphtheria 87-96
Tetanus >90
Pertussis 35-96, recent studies in the UK have shown it to be >90
Hib 94-100
Oral Polio 90-100
Measles 90-95
Mumps 90-98
Rubella >95

Source: Bedford H & Elliman D (2000) Concerns about immunisation. BMJ 320: 240-3.

If immunisation coverage falls below that required for population immunity, epidemics can ensue. In the case of measles, for example, the vaccine has an efficacy level of 90 to 95 per cent. It is estimated that for population immunity, immunisation uptake in the UK must be around 92 to 95 per cent. Whereas, for India it is about 99 per cent.9

Table 5: Immunisation coverage required for population immunity  (UK)
Disease/Vaccine % coverage required for population immunity
Diphtheria 80 -85
Tetanus Not applicable as no person to person spread
Polio 80 – 85
Pertussis 92 -95
Measles 92 – 95
Mumps 90 -92

Source: Moxon E R (ed) (1990) Modern vaccines. A Lancet review. Current practice and new approaches. Edward Arnold, London.

Immunisation of migrants:

While some countries such the United States immigration law requires immigrant visa applicants to obtain certain vaccinations (listed below) prior to the issuance of an immigrant visa this does not seem to be the case for immigrants arriving to the United Kingdome from overseas. Moreover, immunisations in the UK are not compulsory in contrast to some countries where children need to have certificates of completing immunisation prior to admission to nurseries and schools. There is some good stuff on this subject at the Health Protection Agency and Royal College of Nursing websites.

Key messages for messages for primary care practitioners: 1, 10

  • ALWAYS ask new migrants about their vaccine history.
  • Unless there is a reliable history of previous immunisation, children arriving from overseas and staying in the UK should be assumed to be unimmunised and be put on the UK schedule (table 1 above).
  • Children who arrive in the UK part way through their immunisation schedule should be transferred onto the UK schedule and immunised as appropriate for their age.
  • On occasion a child arriving in the UK from abroad may have received an additional fourth dose of diphtheria, tetanus, pertussis or polio around the age of 18-24 months. The routine UK schedule should be applied regardless of this additional dose.
  • Children immunised against measles before their first birthday may still have maternal antibodies and therefore should be re-immunised with MMR and offered a second dose at the relevant age.
  • In case of doubt contact local immunisation co-ordinator for further advice

Refrences:

  1. Health Protection Agency (HPA): Vaccination Immunisation, Jan 2012http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/VaccinationImmunisation/
  2. Department of Health (2006): Immunisation against infectious disease (The Green Book). London: HMSO.https://www.wp.dh.gov.uk/immunisation/files/2012/07/Green-Book-Chapter-19-v4_71.pdf
  3. National Institute of Allergy and Infectious Diseases : Vaccineshttp://www.niaid.nih.gov/topics/vaccines/understanding/pages/typesvaccines.aspx
  4. Centers for Disease Control and Prevention (CDC): Vaccines & Immunizations.http://www.cdc.gov/vaccines/
  5. World Health Organisation -2010: Global immunization data.
  6. British Medical Association (www.bma.org.uk) ,June 2003:Childhood immunisation: a guide for healthcare professionals
  7. www.cdc.gov/nip/publications/fs/gen/Why.htm
  8. Bedford H & Elliman D (2001) Childhood immunisation: the facts. UK: Health Promotion England.
  9. Kassianos GC (2001) Immunization childhood and travel health (4e) Oxford: Blackwell Science.
  10. Royal College of Nursing: Vaccinating children arriving in the UK from overseas… (http://www.rcn.org.uk/__data/assets/pdf_file/0005/78629/002467.pdf)
  11. The History of Vaccination: www.nhs.uk

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