Pneumococcal polysaccharide vaccine uptake in England, 1989–2003, prior to the introduction of a vaccination programme for older adults

Abstract

Objective Following the licensure of 23-valent pneumococcal polysaccharide vaccine (23vPPV) in 1989, a risk-group–only immunization policy was implemented in 1992 in England. The PPV programme was extended in 2003 to include all individuals 65 years and over. In England, this was phased in over 3 years. To ascertain the performance of the risk group policy in those 65 years of age and over and provide a baseline to estimate the impact of the universal elderly programme.

Methods Information was gathered on vaccine uptake for the period 1989–2003 in England from a national survey of general practitioners (GPs) through NHS primary care trusts (PCTs), the prescription cost analysis (PCA) system and the General Practice Research Database (GPRD).

Results Between 1991 and 2003, 4.5 million doses of PPV were prescribed. The GP survey found that by 2003, 29% of those 65 years and over of age and 36% of those 80 years of age over had received PPV. Sixty-two per cent of general practices had implemented a risk-group–only policy, 14.4% had targeted all those 65 years of age over and 14.2% had targeted all those 75 years of age over. The GPRD study found that 38% of those 65 years over and 41% of those 80 years over fell into one or more high-risk groups. By 2003, 36.6% of the high-risk group and 30.2% of all those 65 years over had ever been vaccinated. Vaccine uptake increased with age, with 52.3% of the high-risk group and 37% of all those 80 years over having ever been vaccinated.

Conclusions A large proportion of those in risk groups remained unvaccinated with PPV in 2003. Formal evaluation of the impact and effectiveness of the universal elderly immunization programme will be required.

Introduction

Streptococcus pneumoniae (pneumococcus) is a major cause of invasive bacterial infections particularly in young children, in the elderly and in groups at higher risk such as those with chronic heart and lung disease. In addition, it is responsible for the majority of community-acquired pneumonia in the elderly and otitis media in young children.¹

Since 1992, a 23vPPV has been recommended in England for individuals at higher risk of invasive pneumococcal infection over the age of 2 years.² The present schedule recommends revaccination for certain risk groups after 5 years.³ Although current evidence demonstrates that the polysaccharide vaccine is not effective in protecting against non-bacteraemic pneumococcal pneumonia, otitis media or exacerbations of chronic bronchitis, limited clinical trial and observational evidence do suggest that the vaccine prevents pneumococcal bacteraemia in 50–70% of healthy adults.⁴ On this basis, in 2003, the UK Department of Health extended the pneumococcal polysaccharide immunization programme to include all individuals 65 years and over, with the aim of reducing the burden of invasive pneumococcal disease in the older population. In England, this programme was introduced in August 2003 and was phased in over 3 years: from August 2003, all those aged 80 years and over were offered 23vPPV; from April 2004, the programme was extended to include all those aged 75 years and over; and from April 2005, the vaccine was offered to all those aged 65 years and over.⁵

This article presents data on PPV uptake in the elderly before the launch of the universal elderly pneumococcal immunization programme.

Methods

Information on the uptake of the 23vPPV for the period 1989–2003 was obtained from three sources: a national PPV uptake GP survey, the prescription cost analysis (PCA) system and the General Practice Research Database (GPRD).

National PPV uptake GP survey, England, 1993–2003

Historical data on the number of people aged 65 years and over immunized before the start of the pneumococcal immunization programme from the period 20 August 1993 to 20 August 2003 were sought from all general practitioners (GPs) in England in 2003. Information was gathered on the pneumococcal immunization policy in place before the start of the national immunization programme for the elderly in 2003, including whether all older age groups were routinely immunized. Vaccination status was recorded for all patients currently registered at the general practice, and this did not include patients who had died or who had moved to another practice. Data collection forms were either emailed or posted to each general practice by their responsible primary care trust (PCT). The information was collated by each responsible PCT and entered onto a standardized Access database. Data by the PCTs were collated and analysed centrally by the Health Protection Agency. The national collection was voluntary.

The proportion of the England population represented by the returned data was calculated from the mid-2002 population statistics (Source: Office for National Statistics).

PCA—PPV prescription items dispensed in the community, England, 1990–2003

Data on the number of prescription items dispensed in England each year from 1990 to 2003 were obtained from the PCA system. Data are based on an analysis of all prescriptions dispensed (but not necessarily administered) in the community—by community pharmacists, appliance contractors, dispensing doctors—and prescriptions submitted by prescribing doctors for items personally administered in England. Total prescriptions include those from GPs, hospital doctors, nurses and dentists dispensed in the community in England. This includes prescriptions written in Wales, Scotland, Northern Ireland and the Isle of Man but dispensed in England. The data do not cover drugs dispensed in hospital or by private prescription. The data do not record patient age or link to patient records.

GPRD, England and Wales, 1989–2003

The GPRD was established in 1987 and is currently managed by the Medicines and Healthcare Products Regulatory Agency (MHRA). It comprises a network of general practices that contribute anonymized patient data to create comprehensive observational data on primary care consultations. Information from 330 general practices contributing to the GPRD in England and Wales was available for the period July 1989–June 2003. This represents ∼6–7% of the general population. Data are regularly updated and validated. Patients were excluded if not registered for the full year (including births and deaths within that year). Patients registered with practices over this period were categorized by age group, gender, risk group and whether they were immunized each year. High-risk patients were defined by Read codes (*) that closely matched the risk groups recommended for pneumococcal immunization.

The total number ever vaccinated by age group each year was estimated from the reported number newly vaccinated each year. For this calculation, a constant age-specific mortality was assumed over the period. The analysis was conducted for all those individuals falling into one or more of the defined medical risk groups and for all adults.

Results

National PPV uptake GP survey

In the survey, 228 of 303 PCTs (75.2%) returned pneumococcal vaccine uptake figures. The remaining 75 non-responders were distributed across the nine regions of England (Table 1). There was a large variation in the response rate (47–94%).

In the 10 years before the start of the national programme, 23vPPV uptake was 36.2% in those aged 80 years and over, 29.8% in those between 75 and 79 years of age and 21.1% in those between 65 and 74 years of age (Table 2). There was a marked regional variation in vaccine uptake (Fig. 1), with the highest uptake in the North East region (80+ years = 50.1%; 75–79 years = 43.4%) and the lowest in the Eastern region (80+ years = 30.8%; 75–79 years = 22.2%). Furthermore, there was a large variation by PCT in the percentage of patients immunized by age group.

Pneumococcal immunization policy before the start of the elderly immunization programme in 2003 was mixed. Almost two-thirds of general practices (62%, 4436/7151) reported following national recommendations and immunized only those individuals falling in at-risk groups. However, some general practices had implemented a policy to vaccinate all those the age of 65 over (14.3% 1021/7151) or 75 years of age over (14.2%, 1013/7151).

If the national vaccine uptake data are applied to the whole of England based on 2002 census figures, ∼2.2 million people aged 65 years and over would have received pneumococcal vaccine in the 10 years before 2003.

PPV prescription items dispensed in the community

Prescribing data for England demonstrate that in the decade between 1993 and 2003, on average 400 000 doses of pneumococcal vaccine were dispensed each year before the start of the programme.

Following recommendation in 1992, after a 2-year lag, the annual number of doses increased dramatically from 1994, with the bulk of the prescribing in the second half of each year. A small peak occurred in 1997. In total, 4.4 million doses of pneumococcal vaccine were prescribed over this period (Fig. 2).

GPRD uptake figures 1989–2003

The number of patients aged 65 years and over registered each year with GPRD ranged from 165 938 to 428 358 over this period. GPRD data demonstrated that 38% of those aged 65 years over and 41% of those aged 80 years over were in high-risk groups for 23vPPV. Increasing pneumococcal vaccine coverage was observed each year from 1992–2003 onwards (Fig. 3). By 2003, the proportion of those aged 80 years over in high-risk group estimated to have been ever vaccinated was 52.3%. Thirty-seven per cent of all those 80 years over of age were estimated to be vaccinated. By 2003, 36.6% of high-risk groups and 30.2% for all those 65 years over of age were estimated to be vaccinated.

Discussion

Main finding of the study

This article provides a summary of the uptake of the 65 years of age over population immunized as part of the targeted PPV programme before the introduction of the universal elderly programme in August 2003. Data on vaccine uptake in risk groups under 65 years of age will be published separately. The article demonstrates that a moderate proportion of people aged 65 years and over had already received pneumococcal vaccine by 2003, with the proportion of people immunized increasing in older age groups, in high-risk groups and in certain geographical regions.

Limitations of the study

There are some potential limitations to this study. The response rate by region varied greatly, with one region having a response rate of <50%. Clearly, this could potentially bias results. The vaccine coverage survey may potentially be biased in that PCTs, which actively recruit patients for a local immunization policy, may be more likely to provide coverage data. Although there was overall temporal correlation between the three data sources, there was an estimated difference between the absolute number of doses prescribed and the actual 2.3 million doses administered from the vaccine coverage survey. There are probably several explanations for this difference, including that the survey data only covered ∼75% of the population, the survey represented doses administered (rather than prescribed), and finally the survey did not include vaccine administered to those under 65 years of age falling into medical risk groups and those falling into groups such as those with splenic dysfunction or nephrotic syndrome that require reimmunization after 5–10 years.⁶

What is already known on this topic

To date, nothing on this topic relating to England has been published.

What this study adds

This study provides baseline information on Pre-vaccine uptake in the 65 age over group before the implementation of the universal 65-year-over old policy.

There were several areas where the study provided additional insights. Although the majority of practices undertook to implement a risk-group–only policy, some practices also undertook to vaccinate all individuals above a certain age. This presumably partially explains the wide variations in vaccine uptake by PCT across England. This wide variation also suggests that uptake can be improved. As has been noted elsewhere, various organizational changes, such as use of planned GP visits and administration by non-GP staff, can be effective tools to increase vaccine uptake.⁷

The dispensing of pneumococcal vaccine was seasonal, suggesting the vaccine was administered at the same time as the annual influenza vaccine in the last quarter of each year. The peak in doses dispensed in 1997 is likely to be because of the promotional activities and availability of a new vaccine on the UK market that year (Pnu-mune, Wyeth). Fluctuations in the yearly prescribing patterns are likely to be because of local health authority/PCT initiatives to target at-risk groups.

In conclusion, to assess the impacted effectiveness of the universal pneumococcal vaccination programme in the elderly, the Health Protection Agency has established enhanced surveillance including components to monitor vaccine coverage and invasive pneumococcal disease incidence. The data presented in this article provide baseline information required to estimate vaccine effectiveness.

Acknowledgements

The authors thank all the general practices and PCT pneumococcal immunization co-ordinators, whose contribution made this possible. The authors also thank Nick Andrews from the Statistics, Modelling and Economics Unit at the HPA Centre for Infections for his statistical advice.

References