PERMISOS Y LICENCIAS

Practitioners were generally supportive of influenza vaccination (Meynaar et al. 1992).

There were a number of reasons why this may have been so. The evidence for

effectiveness of influenza vaccination had been widely publicised. This was achieved

through the literature (DiGuiseppi 1996), national guidance (Begg and Salisbury 1996),

regular updates from the Chief Medical Officer (Department of Health 2001a), evidence

based journals which were known to be widely read by general practitioners (Coleman

and Nicholl 2001) such as Effectiveness Matters (NHS Centre for Reviews and

Dissemination 1996), Bandolier (Moore 1995) and Clinical Evidence (Marrie 2001) as

well as the mass media. There was some dissention to these views including the argument

that influenza may comprise only a small proportion of winter respiratory infections

responsible for illness, admission or death compared with other viruses (Long et al. 1997;

Nicholson et al. 1997) or that excess winter deaths could be due more to the effect of cold

weather than to influenza (Donaldson and Keatinge 2002).

There was less support amongst practitioners for pneumococcal compared to influenza

vaccination (Kyaw et al. 2001; Bovier 2002). Whilst national guidance promoted

pneumococcal vaccination (Begg and Salisbury 1996), and advice issued from the Chief

Medical Officer to give pneumococcal vaccination together with influenza vaccine

(Department of Health 1997) this direction was contradicted by the suggestion that there

was little evidence to pursue the policy of pneumococcal vaccination (British Thoracic

Bandolier* (Moore 2000) and peer-reviewed journals (Keeley 2002).

The benefits of influenza vaccine had been publicised in Bandolier using the concept of

numbers needed to treat (Moore 1995). For elderly patients aged 60 years and over,

between 9 and 20 patients needed to be vaccinated to prevent one case of influenza. In

contrast, the incidence of pneumococcal infection, particularly so-called invasive

pneumococcal infection, such as bacteraemia or septicaemia was known to be much

smaller. As a result, although relative risk reductions with pneumococcal vaccination

were comparable or even greater in some studies compared with influenza vaccination the

absolute benefits were at least two orders of magnitude smaller. In the Canadian

systematic review for example, risk reductions for vaccine-type pneumonia and systemic

pneumococcal infections were 73% but because the baseline risk of pneumococcal

bacteraemia was much lower, at around 50 cases per 100,000 people over 65 years of age,

the number needed to treat† was considerably higher. Hutchison calculated that 2520

elderly people would need to be vaccinated to prevent one case of pneumococcal

bacteraemia each year (Hutchison et al. 1999). This meant that assuming vaccine costs of

£10 per pneumococcal vaccine compared to £5 per influenza vaccine the cost per case

prevented was £25,000 and £40 respectively. This illustration excluded hospital and other

indirect costs which were often much greater for a case of pneumococcal bacteraemia

because this was a more severe illness, likely to require more time in hospital and require

greater resources, such as intensive care, for treatment. However, this calculation

*

Bandolier is particularly quoted here because it was one of the flagship periodicals of the evidence based medicine movement and the debate on the efficacy of pneumococcal vaccination highlighted here.

†

The number needed to treat is calculated as the inverse of the absolute risk reduction and is a useful standardised and readily understandable measure of clinical effectiveness because it incorporates disease prevalence.

strikingly demonstrated the basis for the broad difference in perceptions about the cost-

effectiveness of the two vaccines.

Despite the importance of patient and practitioner barriers, such as knowledge and

attitudes to vaccination, positive attitudes were not always translated into improvements

in care (Hulscher et al. 1997a). Another important reason for failure to vaccinate was a

lack of systems to identify or contact those patients who were eligible for vaccination

(Bedford et al. 1997). One common reason why doctors and nurses did not vaccinate

patients was that they forgot to. Indeed, in one study this factor correlated most closely

with the doctor’s vaccination rate (Metersky et al. 1998). Vaccination was forgotten for

two main reasons. Firstly, practitioners believed they were vaccinating more patients than

they actually were, so were overconfident in their estimate of how well they were doing

and this reduced the pressure to vaccinate. Practitioners’ overestimation of their own

performance has been a consistent finding from many audit studies looking at a variety of

health care activities. Secondly, practitioners’ attention was diverted away from the issue

of vaccination by the presenting medical problem (Noe and Markson 1998) or other more

important clinical issues (Hershey and Karuza 1997; Rushton et al. 1994). Another reason

for practitioners being unable to vaccinate was that the problem presented to the doctor

by the patient was an acute illness which necessitated postponing vaccination (Szilagyi et

al. 1994). There were also many occasions when the patient refused vaccination (Hershey

and Karuza 1997; Metersky et al. 1998) for the various reasons cited above (see 3.6)

Some health care workers were also concerned about side effects of influenza and

pneumococcal vaccine and uncertain about guidelines or vaccine effectiveness (Ballada et

al. 1994), negative attitudes which were prevalent even amongst respiratory physicians

(Sockrider et al. 1998). These negative attitudes may have reduced the likelihood that

health workers offered vaccination to their patients and such attitudes were also shown to

adversely affect vaccine uptake amongst health care staff themselves (Nafziger and

Herwaldt 1994; Beguin et al. 1998; Yassi et al. 1994; Watanakunakorn et al. 1993).

There were also differences between influenza and pneumococcal vaccination in this

respect with less support amongst practitioners for pneumococcal than influenza

vaccination (Kyaw et al. 2001; Bovier 2002).