changes in practice
Two months ago the Government announced the largest and most complicated set of changes to the recommended immunisation schedule
Professor Adam Finn explains the changes
The recent changes to the vaccine schedule were welcomed by paediatricians but also prompted alarmist reports in the media.
The new childhood schedule is summarised in the table below. The main changes are:
·introduction of the new pneumococcal vaccine
·dropping of one of the Men C first year doses and giving it at 12 months instead
·Hib booster at 12 months.
The introduction of these changes is
expected to start before this summer. The
related catch-up programme will, presumably, follow thereafter and will take at least several months. Paediatricians particularly welcomed the arrival of the pneumococcal conjugate vaccine, as many had been impatiently waiting for it for several years (and often independently sought doses of the vaccine for their own children).
The media concerns did not relate to the new vaccine specifically but concerns that
the number of vaccines now recommended is too large and too great an immuno-
logical burden for infants to cope with.
The new pneumococcal vaccine
Pneumococcus is a common bacterium,
virtually all children have been exposed to it by the time they reach school age. Usually it colonises the nose and does not cause significant illness. However, it does cause trouble often enough for it to be a major public health problem.
The commonest manifestation is otitis media. Pneumococcus is one of several
bacterial species associated with this extremely common cause of presentations of young children to primary care. The illness probably occurs due to the combined effects of pneumococcal colonisation of the nose and intercurrent viral infection.
The second commonest manifestation of pneumococcal infection is, as you might expect from the name, pneumonia. Again most of this morbidity is probably dealt with by
antibiotic treatment in primary care, but a significant proportion of children with lower respiratory tract infection due to pneumo-coccus present to hospital, and of those a significant number require admission.
Invasive disease due to pneumococcus is comparatively rare, but is associated with
a high rate of death and sequelae when it
occurs, even with prompt diagnosis and treatment. Around a third of cases are pneumococcal meningitis. Among the causes of post-neonatal community-acquired bacterial meningitis, the devastation of pneumococcus is equalled only by tuberculosis.
The main facts about pneumococcal infection are summarised in the box, right.
Subtler benfits are also expected. Rates of nasal carriage and transmission of pneumococcus are highest in young children. Immunisation reduces carriage rates of the vaccine strains. The resulting herd immunity
effect brings falling rates of disease in unimmunised older children and adults especially parents and grandparents.
Since pneumococcal pneumonia is a
significant problem in the elderly, these benefits are important and we can expect at least as great an impact from the programme here as directly on children.
The vaccine has been used widely in young children in the US since 2000 and licensed in Europe for more than five years.
It has been used in the UK increasingly over that period in children at high risk of pneumococcal infection. No concerns have been raised about its safety, the only recorded problems being mild fever and local redness in fewer than one in five children.
It is not the same vaccine as the 23-valent pneumococcal vaccine (commonly called Pneumovax) used widely in the elderly and other high-risk groups.
Newer formulations of conjugate pneumococcal vaccines for children are in the pipeline containing larger numbers of types.
The main consequence of introducing this vaccine is that there will now be three injections at the four-month visit (see panel top right). Obviously this will raise concerns from parents but GPs should be reassured that this is routine in many other countries.
The simplest way to give the three vaccines will probably be to use both legs and one arm.
RCGP immunisation spokesman Dr George Kassianos has suggested giving two injections in one thigh as long as there is a gap of 2.5cm between them. Official guidance on this is expected soon.
Delaying Men C final dose
The Chief Medical Officer made the decision to delay the Men C final dose until 12 months based on two main findings:
·research showing that two doses of Men C provide the same level of protection as three doses in the first year of life
·a booster in the second year will extend protection
The JCVI in its recommendations said the evidence showed there was no incremental difference in antibody titres between the second and third dose but that levels following just one dose were significantly lower than two.
It found no significant benefits when it used mathematical modelling to compare the first-year Men C vaccine and second-
year booster compared with a second-year vaccine alone.
However, disease levels are low at present and are likely to be maintained by herd immunity, and so it agreed with the longer-term strategy of three vaccines.
Delaying one of the Men C doses provides a gap for the first dose of the new pneumococcal vaccine at two months. Giving the DTaP/Hib/IPV and the Men C and the pneumococcal conjugate vaccine at the same time at four months avoids the need for an additional visit in early infancy at a time when parents have to make visits at two and three months already.
While the introduction of the Hib booster in 1992 dramatically reduced the number of cases of Hib disease in children (particularly Hib meningitis) these rates started to creep up in 1998 and so the Hib catch-up programme was introduced.
The CMO introduced the booster in the second year of life in this round of changes to ensure protection throughout early childhood and to reduce the risk of further resurgence in future.
Since Hib is given combined with DTP/
Polio, removing one of the three early doses would have been more trouble than it was worth.
The changes go a long way towards minimising the number of visits and injections needed while still allowing all the necessary doses to be given.
Finally, the availability of the combined Hib/MenC vaccine allows these boosters to be given as a single injection.
2 months Five-in-one (diphtheria, tetanus, polio,
whooping cough and Hib meningitis)
3 months Five-in-one
4 months Five-in-one
12 months New combined Hib/meningitis C vaccine
13 months MMR
A pneumococcal vaccine catch-up programme will be introduced to ensure that children up to two years of age who are most at risk of pneumococcal infection are also offered the vaccine
The case for a new vaccine
· Pneumococcal infection is most common in babies, young children and the elderly
· There are 5,000 cases of invasive pneumococcal disease in England and Wales each year and around 530 of these are in children under two years
· Estimates vary but around 50 children under
two will die from invasive pneumococcal disease
each year and two-thirds of these deaths are from meningitis
· Up to 50 per cent who survive pneumococcal meningitis will be left with permanent disabilities including deafness, cerebral palsy or blindness
'Will all these vaccines overwhelm my child's immune system doctor?'
'Although we now give children more vaccines, the actual number of antigens they receive has declined. Whereas previously one vaccine, smallpox, contained about 200 proteins, now the 11 (US) routinely recommended vaccines contain fewer than 130 proteins in total.
Two factors account for this decline: first the worldwide eradication of smallpox obviated the need for that vaccine, and second, advances in protein chemistry have resulted in vaccines containing fewer antigens (eg replacement of whole-cell with acellular pertussis vaccine).'
'Do multiple vaccines overwhelm or weaken the infant's immune system?' Offit et al. Pediatrics (US) vol 1, No 1 January 2002, pp124-129
'It may seem as though giving an injection that contains many vaccines all at once is a lot for a baby to cope with. In fact babies have an ability, right from birth, to cope with lots of different germs.
The body is constantly surrounded by germs and has to react to them in different ways. The advantage of being immunised rather than catching the disease is that the vaccine uses only part of the germ, or, if the whole germ, it is either killed or toned down ('attenuated').
In this way, the challenge to the immune system is less than that from the disease, but it is enough to produce protection.
In 2002, the Immunisation Safety Review Committee of the American Institute of Medicine made a detailed examination of all the evidence about the effects of multiple immunisations on a baby's immune system.
It concluded there was no evidence to support the suggestion that multiple immunisations overwhelm the immune system. It strongly supported the continuing use of vaccines against multiple diseases.
Giving the vaccines separately would have some disadvantages. Since babies need three doses of each of the infant vaccines to develop full immunity, giving them all on separate occasions would mean 18 separate injections. This would be very unpleasant for the baby and for most parents. Unless the interval between each was short, this would mean delaying baby's final protection.'
Taken from Great Ormond Street Hospital, Institute of Child Health website: www.gosh.nhs.uk/immunisation/faqs.html
Adam Finn is professor of paediatrics at the University of Bristol
competing interests Professor Finn has undertaken research and done consultancy work for his employer,the University of Bristol, paid for by vaccine (including pneumococcal) manufacturers