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chapter 7 communicable disease and immunisation

Introduction

Infections continue to be a major public health problem in Scottish children. Significant progress has been made in reducing their impact, but much remains to be done to reduce disease and suffering, especially in infancy. One particular success story has been the effectiveness of immunisation programmes in preventing communicable diseases.

Immunisation played a major role in ending the large outbreaks and epidemics of childhood infections seen in the early 20th century and the substantial death and disease they caused. Children are now routinely vaccinated and protected against measles, whooping cough, Haemophilus influenzae type b (Hib), meningitis C (Men C), mumps, polio, diphtheria, tetanus and rubella. Advances in epidemiology, microbiology, immunology and biotechnology have led to the development of safer, more effective vaccines along with new vaccines for previously unchallenged infectious diseases.

Infections in early years: the burden on children and families

In 2006 there were 248 deaths in children under 1 year in Scotland, with five of these due to infections. In the 1-4 year age group, infections accounted for 12.8% (6) of the 47 deaths recorded. While deaths are now relatively rare, infections still exact a high cost on children. 13,640 children under 5 were admitted as emergency cases to Scottish hospitals with a diagnosed infection. This was 42% of all emergency admissions in that age group (table 1). Over half of those infections were respiratory.

Table 1: Diagnoses of infections in children under 5 admitted as an emergency into acute hospitals in Scotland
(year ending 31 March 2006)

Source: ISD Scotland ( SMR01)
Extracted November 2006

An estimated 50% of GP consultations in children are due to infections, especially respiratory infections. Streptococcus pneumoniae, Respiratory Syncytial Virus ( RSV) and influenza A cause most of these infections and consultations for all three peak in the under 5s ⁸⁴. Data from Scottish Practice Team Information ( PTI), which represents 5% of primary care coverage across the country show that acute upper respiratory tract infections are the commonest reason for children under 5 seeing a GP. Other infections are frequently diagnosed (Table 2).

Table 2: - Top 10 reasons for attending primary care - GP consultations for children aged less than 15, at a sample of Scottish practices
(Year ending March 31 2006)

Dark shading indicates conditions caused by infections
Pale shading indicates conditions often caused by infections
No shading indicates conditions that are mainly non-infectious

Source: PTI
1 Rates are per 1000 population and are standardised by deprivation (and age/sex where applicable).
2 Excluding acute pharyngitis, acute tonsillitis, acute laryngitis and tracheitis.
3 Excluding infections and malignancies.
4 Excluding meningococcal, skin, respiratory and urinary tract infections, gastroenteritis, and osteomyelitis.
5 Excluding influenza, pneumonia, acute bronchitis, acute bronchiolitis, chronic sinusitis, chronic disease of tonsils and adenoids and malignancies.
6 NEC= Not Elsewhere Classified.

For infections where no vaccine currently exists, or where questions remain about the effectiveness of the available product, continued vigilance and surveillance; early recognition of signs and symptoms and appropriate management and treatment through primary care combine to reduce the impact of these infections.

Inequalities in health - infection and immunisation

The greatest burden of childhood infections in terms of both morbidity and mortality is seen among the most deprived sectors of the population. Deaths from infectious or respiratory diseases are 2.5 to 3.0 times higher in children in social class V (unskilled) compared with Social class I (professional). One study showed increasing hospital admission rates with increasing social deprivation for all respiratory infections in all age groups, but particularly those aged less than 5, where admission rates were nearly twice as high in the most deprived quintile compared to the least. This pattern is also seen in primary care. Separate studies have shown higher morbidity from infections in children from more deprived backgrounds for RSV, meningococcal infection and invasive pneumococcal disease ( IPD) ⁸⁵. But the pattern is maintained for respiratory infections as a whole.

In Scotland deprivation impacts on immunisation rates. The Scottish Immunisation Recall System ⁸⁶ showed that the average primary immunisation uptake was 92.1% in the most deprived group of children (Carstairs: depcat 7) compared with 96.8% in the least deprived group. Children in more deprived groups were also vaccinated at a later age.

Figure 1 Cases of invasive pneumococcal disease ( IPD) in children under 5 in Scotland, by yearly period

Invasive bacterial infections

Following the control, through vaccination, of Meningitis C and Haemophilus Influenzae group B - Streptococcus pneumoniae has emerged as one of the most common remaining invasive bacterial infections. Every year 60 - 100 children in Scotland suffer from invasive pneumococcal disease (figure 1). This infection can have serious life-threatening consequences including meningitis, septicaemia and acute pneumonia. Non-invasive infections requiring treatment, especially middle ear infections (otitis media), also affect many children. Otitis media is one of the top ten reasons for primary care consultation for under 5 year olds in Scotland ( PTI data - table 2)

In 2006 a vaccine against pneumococcal infection was introduced into the childhood immunisation schedule. This vaccine, a pneumococcal conjugate vaccine ( PCV), protects against seven vaccine serotypes. These serotypes caused 50% to 76% cases of IPD in children under 5 in Scotland (2003 - 2005). The new vaccine has an excellent safety profile when given alone or at the same time as other routine immunisations. There is also evidence that the vaccine may provide cross protection for other pneumococcal serotypes. It also appears to prevent asymptomatic carriage of the bacteria and could have an indirect protective effect for non-immunised individuals.

New vaccination schedule

In September 2006 changes were made to the childhood immunisation schedule following recommendations of the Joint Committee on Vaccination and Immunisation. This introduced the new PCV vaccine and brought in other modifications. The main changes were:

• The addition of the pneumococcal conjugate vaccine ( PCV) at 2,4 and 13 months of age;
• One dose of Men C vaccine at 3 months and 4 months of age;
• A booster dose of Hib and Men C vaccine (given as a combination vaccine) at 12 months, to continue protection against these infections later in life.

The new immunisation schedule is more complicated because infants are now offered different combinations of vaccines at the 2, 3 and 4 month visits; are given three injections at 4 months of age and are called for an additional visit. The first cohort of Scottish children to begin the new schedule are not yet old enough to have completed their primary immunisations but vaccination uptake will be monitored carefully to ensure that the high uptake rates of previous years are not adversely affected by the changes in the immunisation programme.

Figure 2 Vaccination uptake rates at 24 months in Scotland (1995 - 2006)
(Source: ISD)

Immunisation uptake

The uptake rates in Scotland as a whole are very good with above 95% for diphtheria, polio, pertussis, tetanus, Hib and Men C by age 24 months (figure 2). Uptake of Measles Mumps Rubella ( MMR) vaccine at 24 months was 92.1% in 2006, an improvement on 2005, continuing a steady climb in coverage since the low point in June 2003 (85.8%) following the Wakefield controversy. The Scottish Government set a new HEAT (Health, Efficiency, Access, Treatment) target in 2006 of 95% uptake of at least one dose of MMR by the age of 5, to maximise protection in children before they begin school. In 2006 uptake at age 5 reached 93.8%, and has continued to improve in the first half of 2007 (to 94.4%).

Pneumococcal vaccination

The first cohort of children to receive three PCV doses are still too young to have completed the full three-dose course, but early indications are that the vaccine uptake has been good, with 95.1% receiving the first dose of PCV. In addition 85.5% of older children, offered a single dose of vaccine as a catch-up, had been vaccinated by August 2007. Both of these figures will continue to rise. The first official figures for PCV uptake will be published in December 2007.

Conclusion

Infectious diseases still pose a considerable threat in early life with large numbers of infants, suffering from infections, having to attend their GP or being admitted to hospital as an emergency. Immunisation is and will continue to be one of the priority public health measures to protect children from these dangers.

In the coming years, a number of challenges face those responsible for delivering immunisation programmes. Foremost among these are:

• Continuing efforts towards reaching the new target of 95% uptake of one dose of MMR by age 5.
• Maximising the uptake of the new PCV vaccine in children under 2.
• Retaining the current high levels of vaccination coverage, during the changeover period to the new immunisation schedule and beyond.
• Planning and preparation for the introduction of Human Papillomavirus ( HPV) vaccine in girls aged 12 - 13 in a programme beginning in 2008 with a catch-up campaign for older girls over the subsequent 2 to 3 years.

"The uptake rates in Scotland as a whole are very good with above 95% for diphtheria, polio, pertussis, tetanus, Hib and Men C"

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