Memorandum by Dr Natasha S Crowcroft,
Consultant Epidemiologist, PHLS CDSC
I write as an individual working in the Public
Health Laboratory Service (PHLS) Communicable Disease Surveillance
Centre (CDSC) Immunisation Division. My submission focuses on
vaccine preventable disease, particularly on aspects relating
to prevention and surveillance.
1. What are the main problems facing the
surveillance, treatment and prevention of human infectious disease
in the UK?
The UK is internationally respected for the
high quality of its vaccination programmes including surveillance
of vaccine preventable disease. For vaccination programmes, surveillance
includes not only monitoring disease incidence, but also vaccination
coverage, population susceptibility through serosurveys, and vaccine
adverse events. Vaccination is recognised by the World Health
Organization (WHO) to be the most effective health intervention
after provision of clean water, but the lives saved by a well
implemented programme are often taken for granted.
When vaccination coverage is high and the infections
rare, it becomes hard to maintain the priority of surveillance.
The enormous benefits of vaccination are taken for granted and
this presents one of the main problems in obtaining sufficient
core resources for surveillance. Some of the key policy work being
carried out at national level for the UK is supported through
grant funding rather than with core support.
When vaccine preventable infections become rare
it is important for surveillance to be even more intensive (and
expensive) than that required when they are more common. This
is important to monitor the efficacy of the vaccines in use and
to meet WHO requirements. Surveillance becomes more difficult
Clinical notifications are incomplete
(grossly so for infections such as pertussis where probably less
than one in 10 infections are notified).
The positive predictive value of
clinical case definitions falls with falling disease incidence.
For example, most infections notified as measles now prove not
to be measles, where 20 years ago the majority would have been
Important information in routine
laboratory data and notifications is often missing, such as vaccination
status and batch numbers of vaccines. For example, nearly 90 per
cent of hepatitis A virus infection laboratory reports have no
information about whether the infection may have been acquired
In response to these challenges we have moved
from using clinical notifications to requiring laboratory confirmation
and from passive surveillance to enhanced surveillance for diphtheria,
tetanus, pertussis, polio, measles, mumps, rubella, Haemophilus
influenzae b, and meningococcal infection. Enhanced surveillance
improves the specificity of reporting but does not necessarily
improve its sensitivity (completeness).
For some diseases detailed microbiological surveillance
is required for public health purposes. For examples:
Pertactin typing of Bordetella pertussis
has been carried out to examine whether in the UK any immune selection
by vaccination can be observed that might lead to a resurgence
of pertussis as seen in the 1990s in the Netherlands.
Subtyping of Neisseria meningitidis
to see whether implementation of the Group C meningococcal vaccination
programme may lead to capsular switching or a resurgence of a
different serogroup. Much of this typing is carried out solely
for public health purposes and has no implications for individual
Vaccination coverage data is a critical tool
for monitoring the delivery of the programme and has been obtained
on behalf of the Department of health by CDSC from the Child Health
Computer System of Community Trusts. Although the data are not
perfect, they have been amongst the best in the world as few countries
have a population-based system of measuring coverage. Following
the dissolution of health authorities, Primary Care Trusts have
the prime responsibility for the health of local populations.
Some District Immunisation Co-ordinators now work in different
organisations separating them from the locus of responsibility
and sometimes from access to coverage data. For example, some
of those who are paediatricians have moved to the local acute
hospital trust. The problems from the managerial re-organisation
are exacerbated by new administrative boundaries. Furthermore,
PCTs' responsibilities are more easily interpreted in terms of
GP practices than geographically defined populations and unregistered
patients risk being neglected. Some GPs are frustrated because
they are asked to provide different data for their vaccination
target payments from that required for the Child Health System.
Some PCTs are examining ways to collect coverage data directly
from GPs which will not easily be referred to a geographical population.
Maintenance of coverage data is currently being challenged by
such health service re-organisation.
Serosurveys of susceptibility have been carried
out by the PHLS using its network of laboratories. It is not clear
where lies the future of this surveillance if, as appears to be
the current model, the new Health Protection Agency passes the
whole laboratory network over to the NHS.
Vaccine adverse events surveillance, the responsibility
of the Medicine Control Agency, relies primarily on passive reporting
through the "Yellow card" scheme. This is known to be
incomplete. In the current climate where parents fear the vaccines
much more than the diseases they prevent, a current challenge
is to improve the system of adverse events surveillance to be
able to provide more accurate information and faster detection
of problems especially as new vaccines are added to the programme.
The rarity of vaccine preventable diseases following
the success of the programme also makes the task of convincing
parents and recipients of vaccines of their necessity. Parents
and health care workers now have little experience of how severe
vaccine preventable infections can be and often do not realise
how quickly they can resurge if vaccination coverage falls, as
seen during the large epidemics of whooping cough which followed
the pertussis vaccine scare in the 1970s. The issue here is of
risk communication and how to improve the media's and the public's
understanding, not just of science but also of the robust and
independent public health infrastructure which underpins the whole
For health care workers delivering the vaccination
programme in primary care training has been extremely limited.
Practice nurses and health visitors receive little training beyond
the basic practical skills and this puts them in a difficult position
when trying to act as advocates for immunisation with parents.
A joint venture between PHLS and City University has recently
started providing university level training on the rationale and
scientific basis of vaccination aimed at primary care professionals,
to our knowledge the only training at this level currently available
The requirements to protect data may threaten
the quality of surveillance. This is a particular challenge for
adverse events surveillance where data linkage studies (which
require patient identifiable information) have proved enormously
powerful in enabling us to examine hypotheses that a particular
vaccine is associated with an adverse events extremely rapidly.
For example, a link was proposed in recent years between oral
polio virus vaccine and intussusception. This hypothesis was examined
in a data linkage study and disproved rapidly. In order to have
a sensitive threshold to detect real adverse effects of vaccines,
public health authorities should examine every possible serious
vaccine reaction and provide reassurance, estimate risk or advise
withdrawal of the vaccine in question, as soon as possible. Such
sensitivity to examine every allegation means that most of the
analyses carried out are likely to prove negative and should be
as fast as possible to avoid unnecessary damage to the programme.
2. Will these problems be adequately addressed
by the government's recent infectious disease strategy, Getting
Ahead of the Curve
It is not clear yet whether "Getting Ahead
of the Curve" (GAC) will address the problems outlined. The
main area of concern is public health microbiology. As outlined
above, vaccine preventable disease surveillance relies enormously
on close multidisciplinary collaboration between microbiology
and public health. The existing network of Public Health Laboratories
Enhanced national surveillance of
vaccine preventable disease.
Rapid development and implementation
of evidence-based guidance for investigating and controlling infectious
diseases, such as the Guidance on Rash and Exposure to Rash in
pregnancy produced by the PHLS.
Rapid development of advanced reference
diagnostic methods such as polymerase chain reaction for pertussis,
and genotyping of hepatitis A virus infection.
Development and implementation of
standard operating procedures for diagnostic and public health
microbiology, such as the throat swab screening for Corynebacterium
diphtheriae and C.ulcerans standard operating procedure which
is implemented in almost all Public Health Laboratories but only
around half of NHS laboratories.
It is not clear in GAC how such developments
could come about or be as effective because the laboratory network
will no longer exist and local autonomy will increase, so local
priorities may hamper response to national priorities.
The proposal in GAC to modernise the collection
of vaccination coverage data is welcome although the recommended
development is still awaited.
Aspects of surveillance relating to the vaccination
programme not really addressed by GAC are adverse event surveillance
and training of primary care staff.
Adverse events surveillance should
be as good as disease surveillance.
Minimum standards are needed for
the training of health care workers delivering the vaccination
programme and should be required by PCTs for practice nurses,
health visitors and GPs. Practice nurses in particular experience
difficulties obtaining time and financial support for training
and so would benefit from managerial support for this from the
3. Is the UK benefiting from advances in
surveillance and diagnostic technologies; if not, what are the
obstacles to doing so?
The PHLS has provided an efficient channel for
rolling out advances in surveillance and diagnostic technology.
Although the implications of GAC are not fully defined, current
indications are that the dismantling of the network is likely
to undermine future capacity. Re-organisation of health care at
local level is a further obstacle weakening established relationships
between local public health and microbiology which support detection
of vaccine preventable infections and monitoring of vaccination
Public health legislation requires that statutory
notifications be made in writing and as a result completeness
of reporting is low for most infections. Changes in the law and
agreement on transfer of patient identifiable information for
public health purposes with improved use of internet technology
might enable improved completeness of reporting.
Data linkage is an important tool for disease
surveillance, estimation of priorities for existing and new vaccines
and adverse events investigation. Greater use could be made of
several large data sets including the General Practice Research
Database (GPRD) and Hospital Episode Statistics (HES), especially
if access to the data and timeliness of its availability were
improved and greater data linkage employed through implementation
of the new NHS number. Requirements of patient confidentiality
also threaten the ability to carry out data linkage studies.
Near patient testing has exciting potential
to improve specificity of diagnosis in primary care of infections
such as respiratory syncytial virus (RSV) and influenza. Careful
consideration needs to be given to how such new technology can
be incorporated into laboratory surveillance.
In providing greater flexibility of NHS services
walk-in clinics are developing which may lead to some cases being
lost to surveillance which may have been detected previously.
4. Should the UK make greater use of vaccines
to combat infection and what problems exist for developing new,
more effective or safer vaccines
Vaccines offer the best opportunity to control
infectious diseases with high incidence such as pneumococcal infection
as well as to combat rising antibiotic resistance. New vaccines
on the horizon include licensed vaccines such as new conjugate
pneumococcal vaccines and varicella zoster virus vaccine and vaccines
under development including new influenza vaccines (live attenuated),
Group B meningococcal vaccines, RSV vaccines. However, with the
challenges to the existing programme in the UK including parents
(unfounded) fears that vaccines may overload an infants' immune
system it may prove difficult to add additional vaccines to the
programme. Better public understanding of science and of public
health is required. Implementation of vaccination programmes for
adults are even more challenging than for children. For example,
in the USA the adult 10 yearly tetanus booster programme has uptake
of only around 50 per cent although vaccination is generally supported.
The first problem faced in developing new more
effective or safer vaccines is the enormous resource necessary
to meet safety requirements. For some infectious diseases, vaccines
have not yet been developed because the characteristics of the
organism make it harder to control than the organisms for which
existing vaccines were developed. For example, unlike measles,
RSV causes multiple infections throughout life. It is harder to
develop a vaccine which stimulates long term immunity as this
requires an improvement on nature, with no effective natural immune
response to mimic. In addition, a previous RSV trial vaccine (formalin
inactivated) caused a worsening of RSV infection and so the pharmaceutical
industry is rightly cautious as a result.
Sometimes there is a trade off between safety
and effectiveness. For example, many countries have moved to using
acellular pertussis vaccines from whole cell vaccines because
adverse reactions are less frequent. However, nearly all acellular
vaccines are less effective than a good whole cell vaccine.
New challenges come from advances in medicine
which mean that more vulnerable individuals are surviving and
require protection. For example, there are more surviving infants
born prematurely, immunocompromised individuals (through treatment
or disease) and extremely elderly individuals. Some such individuals
cannot make an immune response to existing vaccines, and for some
live vaccines may be dangerous, so new approaches are required.
5. Which infectious diseases post the biggest
threats in the foreseeable future?
If vaccine scares continue to threaten the national
programmes and the recent falls in coverage of all vaccines continues
(including diphtheria, tetanus and pertussis as well as measles
mumps and rubella) then these diseases will come back. A resurgence
of rubella in children would be expected to be associated with
an increase in congenital rubella syndrome as well. Of the diseases
in the current programme, pertussis is probably the worst controlled
infection and additional boosters may be needed eventually for
adolescents and possibly adults. Pandemic influenza remains a
great threat. The potential for bioterrorist attacks using smallpox
or anthrax has added a new dimension to the threat of vaccine
6. What policy interventions would have the
greatest impact on preventing outbreaks of and damage caused by
infectious disease in the UK?
A public health network of laboratories is required
to support a strong network of public health reference laboratories
and epidemiologists. Public health microbiology is qualitatively
different from diagnostic microbiology. The work of public health
professionals such as consultants in communicable disease control,
regional and national epidemiologists should be fully integrated
with microbiology as the two approaches are complementary and
interdependent. GAC seems to risk enhancing rather than bridging
the divide between public health epidemiology and microbiology.
National standards need to be maintained and
developed for investigation, treatment, surveillance and control
of vaccine preventable diseases. This includes safeguarding and
improving collection of vaccination coverage data and serosurveillance.
Lines of accountability and national priorities need to be clearly
defined so that local priorities do not detract from surveillance
of the national programme. The national vaccination programme
also has to take account of the international context including
requirements of the WHO.
Improving public and media understanding of
science, risk and public health is a major multi-agency policy
area. For example, schools could promote vaccination to protect
all children in the school and as part of the school's duty of
care. It may become important for parents to know the vaccination
coverage of children in the school or nursery which their child
or children attends so they can assess the risk of outbreaks.
Vaccination should be seen as a child protection issuelike
putting on a child's safety belt in the car. Vaccination as a
subject could be incorporated into the national curriculum.
The quality and completeness of information
on vaccinations falls with increasing ageeven by the time
of the pre-school booster the vaccination coverage data quality
is starting to decline, and information on uptake of the school-leaving
booster programme is sketchy. As new vaccines are introduced for
adults, a system for delivering and monitoring adult vaccination
also needs to be developed which is equivalent to the childhood
The quality of vaccine adverse events surveillance
should be at least the same as disease surveillance. Members of
the public could report straight to the medicines control agency.
For example, parents could be given a report form at each vaccination
with a reporting telephone number. To respond rapidly to scares,
an extensive core funded infrastructure should be available including
epidemiologists and mathematical modellers with access to the