Myths in Medicine: Immunisation

Why do immunisation myths exist?

Where ignorance exists myths flourish. The scientific basis of immunisation may be only partly understood by those who give vaccines. Although an increasing proportion of immunisations are being given by general practitioners,2 the typical undergraduate medical curriculum only contains one lecture on the subject. Nurses often actually administer immunisation and are a potent source of advice for parents. Immunisation practice for nurses is, however, often learnt by imitation and from handed down oral “wisdom” rather than being formally taught.

Ignorance has been compounded by the dissemination of contradictory information. Vaccine manufacturers' product inserts, perhaps written with litigation in mind, have frequently been at variance with national policy.3,4 Doctors may refer to a variety of publications other than the official Department of Health memorandum for guidance, including the British National Formulary, the Monthly Index of Medical Specialties, and the Data Sheet Compendium. Each of these three sources has in the past been found to contain incorrect information.3,5 Authoritative guidance did not become available until 1984, when the DoH memorandum was first published.6 Previously there existed only a plethora of leaflets and out of date health circulars on the subject.3 It is therefore hardly surprising that so much misunderstanding has existed among professionals,*RF 7–11* and that confusion and uncertainties have been conveyed to parents.12,13

FIG 1 - Cartoons reveal early scepticism about the vaccine's effects

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The media have not been slow to capitalise on the profession's ignorance and disorganisation, particularly where there is debate about the risks associated with immunisation. Anxiety over the safety of whooping cough vaccine in the mid-1970s was fuelled by newspaper articles and television programmes that highlighted division of medical opinion on the risks of neurological damage from the vaccine and on the indications for immunisation and gave excessive weight to minority opinions.14 In general, the media have been more supportive of immunisation in recent years. However, the considerable attention devoted to the change in supply of measles, mumps, and rubella vaccine in 1992 is a reminder of the potential effect of adverse media publicity.

After the controversy over whooping vaccine immunisation came to be perceived by health professionals as a potentially dangerous and litigious activity.15 Denying immunisation for a mythical contraindication was therefore an easy option, and it was no coincidence that most of the myths operated against immunisation. Many parents shared these myths with doctors and nurses in a subtle conspiracy against immunisation.12,13 Until the target payment scheme was introduced in 1990 there was no great incentive for general practitioners to immunise children.

FIG 2 - The cow “Blossom”, the source of Edward Jenner's vaccine

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In the United States, where immunisations are given by paediatricians, there is a powerful professional lobby which regularly challenges false information before it becomes mythology (although false contraindications are becoming an increasing obstacle to immunisation both in the United States and in other countries, particularly the former Soviet Union.16 By contrast, paediatricians in Britain have only recently become a vocal group; a British Paediatric Association manual on immunisation was not published until 1989,17 and immunisation is rarely performed in hospitals (although immunisation histories are dutifully collected by paediatric house officers). Immunisation was not even a properly recognised health service activity until 1974, when a reorganisation transferred responsibility for community child health services from local authorities to the NHS. The same reorganisation abolished the post of medical officer of health, which had played a vital role in the management of immunisation programmes. This management role was not replaced until 1985, with the appointment of district immunisation coordinators.18

Some common myths

Most myths have a traceable origin, and some contain an element of truth. For example, eczema, a genuine contraindication for smallpox vaccine, became a mythical contraindication for other vaccines, along with other allergic conditions.

“Don't vaccinate breast feeding mothers”

This myth is based on the observation that breast milk contains antibodies that might theoretically interfere with live virus vaccines given by mouth. A review article in a medical journal suggested that the efficacy of oral polio vaccine could perhaps be reduced in breast fed infants.19 Definitive studies have, however, shown that breast feeding does not interfere with this vaccine.20,21

“Children taking antibiotics shouldn't be vaccinated”

The origin of this myth seems to be the recommendation that immunisation should be deferred in an acutely unwell child.22 Many acutely ill children are given antibiotics, and the taking of antibiotics has become a proxy for a substantial illness. However, it is now a common belief that antibiotics somehow interfere with immunisation.7 There is no logical reason why a child taking antibiotics cannot be immunised provided he or she is well on the day of immunisation. Interestingly, even the standard advice is often misunderstood, with people inferring that acute illness interferes with immunisation. The little evidence that exists is ambivalent.23 The true reason for deferral is to avoid difficulties in diagnosis and management should a child's condition worsen after immunisation. It is worth noting that in developing countries ill children are given priority for immunisation when they are admitted to hospital because of the risk of nosocomial infection.

“Don't vaccinate patients with allergies”

This myth probably has several origins. Eczema is a genuine contraindication for smallpox vaccine. In the past, hypersensitivity to eggs was a recommended contraindication for measles vaccine, and hypersensitivity to rabbit protein or fur was a recommended contraindication for one brand of rubella vaccine.6 Some product inserts listed a personal or family history of allergy to a variety of animal products as contraindications for both measles and rubella vaccines. Extreme hypersensitivity or anaphylaxis to eggs is still listed as a contraindication for vaccines for measles, mumps, and rubella, influenza, and yellow fever. Vaccines for measles, mumps, and rubella are also contraindicated in children with allergies to kanamycin and neomycin.22

FIG 3 - In developing countries ill children are given priority for immunisation

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“Vaccination is contraindicated in neurological abnormality”

These were highlighted as contraindications after concern arose over the relation between pertussis vaccine and permanent neurological deficit. Rather than risk being blamed for any subsequent neurological illness, many doctors, in the absence of specific guidance, found reasons not to immunise against whooping cough.8 Some neurological conditions have been listed as genuine contraindications, and this list has changed over the years.*RF 6,22–25* Although it has now been shown that children with stable neurological conditions can be safely immunised,22 it is still recommended that pertussis vaccination is delayed in a child with an evolving condition, on the basis that any subsequent deficit is likely to be blamed on the vaccine.

“Immunisation is now unnecessary”

It is often argued that immunisation is no longer needed as living conditions have improved and treatment is available for many infections.26 In the case of tuberculosis this may be partly true, but for most infections that can be prevented by vaccination it is patently false. There is no specific treatment for polio, measles, mumps, or rubella. Antibiotic treatment for whooping cough is only of use if started early in the illness: the 1977-9 whooping cough epidemic that followed the decline in vaccine uptake in the mid-1970s was the biggest for over 20 years.27 In some cases the incidence of an infectious disease may actually increase as living conditions improve. For example, in developing countries most people, develop hepatitis A early in childhood, when the infection is usually mild or subclinical. As living conditions improve, the average age at which infection occurs rises, leading to an increase in symptomatic infections in older children and young adults. The outbreaks of poliomyelitis that occurred in the 1940s and 1950s have also been attributed to improvements in hygiene.28

Dispelling myths

The best weapons against such myths are knowledge and a positive attitude to immunisation. The current DoH memorandum has a much simplified list of contraindications and highlights the common myths.22 It is important that guidance from other sources is consistent with government policy. A joint advisory group of the British Paediatric Association and the Joint Committee on Vaccination and Immunisation has been established to ensure that advice from the two sources does not conflict. Every effort is being made to ensure that guidance in the British National Formulary is consistent with that of the Joint Committee on Vaccination and Immunisation. The Department of Health holds annual meetings with all district immunisation coordinators, enabling consistent information to be disseminated to those with responsibility for management of the immunisation programme. Before the introduction of measles, mumps, and rubella vaccine in 1988 and Haemophilus influenzae type b vaccine in 1992, coordinators received a set of slides and speaking notes for use at local training sessions to ensure consistency of guidance.

In some districts immunisation advisory clinics have sprung up,10,29 where parents of children with problem medical histories can receive specialist advice. Provided this advice is fed back to general practitioners, these clinics have a valuable educational role as well as ensuring that children with false contraindications are not denied immunisation. Similarly, child health computer systems can now routinely identify children whose parents give consent for immunisation but are not subsequently immunised, thereby detecting failure in immunisation coverage.

Vaccine manufacturers can also contribute by designing product inserts that are less defensive. In the absence of a no fault compensation scheme, however, their guidance will probably always be more cautious than that of the Department of Health or that borne out by research.

The area that has probably received least attention is the reservoir of myths that exists among parents and, perhaps just as important, among grandparents, to whom new parents turn for advice. The material produced by the Health Education Authority is positive towards immunisation but does not specifically tackle myths.