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Carol Joseph, Nichola Goddard, David Gelb, Influenza vaccine uptake and distribution in England and Wales using data from the General Practice Research Database, 1989/90–2003/04, Journal of Public Health, Volume 27, Issue 4, December 2005, Pages 371–377, https://doi.org/10.1093/pubmed/fdi054
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Abstract
Background Routinely collected data from patients registered with general practices participating in the General Practice Research Database (GPRD) were used to analyse influenza vaccine uptake and distribution in England and Wales between 1989/90 and 1996/97. Major changes to influenza immunization policy were introduced in 1998 and 2000 when immunization of the elderly became age related rather than risk related. This new study examines trends in vaccine uptake for high- and low-risk patients and the impact of the policy changes on uptake in the elderly.
Methods Between 0.5 and 2.7 million patients registered with practices participating in the GPRD from 1989 to 2004 were included. Data were examined by age group, medical risk group and evidence of vaccination per study year.
Results Vaccine uptake among high-risk persons aged 65 or more increased from 36.7 per cent in 1989/90 to 72.1 per cent in 2003/04. For the same period, uptake rates for high-risk persons under 65 years increased from 10.8 to 24.3 per cent. For those at high risk, uptake by females was higher in all age groups up to 65 years. Of those that were vaccinated, a higher proportion of the 65 and over were vaccinated in October each year compared with the high risk under 65 (p < 0.001).
Conclusions Coverage among high-risk patients in younger age groups continues to fall well below satisfactory levels, especially among the youngest groups. Government policy should now focus on ways to improve uptake in these patients.
Introduction
Influenza can lead to high levels of morbidity and mortality in vulnerable population groups such as the elderly or those with chronic diseases that put them at risk from respiratory infections. Influenza immunization is the principal and most effective way of reducing this morbidity and mortality. Between 1989 and 1997, the period covered by the first General Practice Research Database (GPRD) study,1 influenza immunization policy in United Kingdom was based on clinical risk only. The first age-related policy was introduced in 1998 when it was recommended that all persons aged 75 or more should be offered vaccine. In 2000, this policy was extended to include all persons aged 65 or more.2
At the time of the first GPRD study, the number of vaccine doses sold each year in England and Wales was known, but no national data were available to link this data with information on who received the vaccine, the rate of uptake in high-risk groups or information on trends over time. The results of the study showed that in high-risk groups of all ages, uptake was below optimum levels although some increase occurred over the period, especially in patients aged 65 and over.
The updated data from GPRD covering the period 1997/98–2003/04 has enabled us to monitor influenza vaccine uptake among the high- and low-risk groups against the changes in policy introduced in 1998 and 2000. It has also provided the opportunity to compare the data with that now obtained through the national monitoring programme for uptake among the 65 and over, introduced by the Department of Health in 2000. This programme was established to evaluate the impact of the new policy, which also included the setting of a national uptake target for the 65 and over in England. The success of this department of health (DP) policy is now well established and uptake rates in the 65 and over now exceed 70 per cent nationally.3 This article reviews trends in annual influenza vaccine uptake in the GPRD data set from 1989 to 2003/04, by age, sex and risk group. Revisions to the data in the original database took place after publication in 1998 and some results may therefore be different to those published in the earlier article.
Methods
The GPRD collects electronic medical records from patients attending more than 350 general practices in the UK and links prescribing data with general health outcomes and exposure events (e.g. an influenza vaccination). Patients registered with general practices in England and Wales between 1989/90 and 2003/04 that participated in the GPRD were included and categorized by age, sex, region (to 1999/2000 only) month of immunization (to 1999/2000 only) and whether immunized. The number of patients involved ranged from less than half a million in 1989/90, 2.7 million in 1992/93 and 1.2 million in 2003/04, covering between 0.6 and 5.02 per cent of the registered population of England and Wales. GPRD data are internally validated to ensure quality of data is maintained across participant practices and that the practices are representative of general practice in England and Wales.4
The study period was divided into monthly periods and ran from 1 July to 30 June each year to capture seasonal influenza incidence and immunization within and outside the normal periods of administration (September to December). Patients were included only if they were registered for the full study year – births and deaths during the year were excluded. Clinical high-risk status for one or more high-risk defining illnesses for influenza vaccine was determined using Oxmis codes5 in the early part of the study and replaced in the later years by Read codes.6 High-risk status once defined for individual patients was retained throughout the length of the study because of the chronic nature of the diseases used to determine risk status. Patients with no recorded risk were labelled as low risk. High- and low-risk patients aged 75 or more were combined into one high-risk group in 1998/99 because of the change in vaccination policy. Likewise, in 2000/01 both high- and low-risk patients aged 65–74 were added to this group to take account of the further government change to vaccination policy.
The percentage of those immunized per study year was calculated by age group, sex and risk status. The variation in annual vaccine uptake was investigated by logistic regression modelling for a relationship between vaccine uptake, study year, age group, sex and risk status. For each strata the presence of a quadratic term for study year was tested for, to find a better fitting model for data which may not be particularly linear.7 Comparisons between GPRD data and data from the DH national influenza vaccine monitoring programme for uptake among patients aged 65 years or more were made for the years 2000/01–2003/04.
Results
Risk status and vaccine uptake
In 1989/90 the proportion of all patients in the sample that were defined as high risk was 13 per cent. This proportion increased yearly, reaching 20 per cent in 1997/98. In 1998/99 and 2000/01 when age-related policies replaced risk-related policies, the proportions increased to 24.4 and 30.5 per cent, respectively.
For all ages and high- and low-risk groups combined, overall vaccine uptake increased from 6.4 per cent in 1989/90 to 17.5 per cent in 2003/04. For the same years, the rate in the high-risk group increased from 20.8 to 42.5 per cent, respectively. In the low-risk group the rate was 4.3 per cent in 1989/90 and 10.8 per cent in 2003/04.
Age, sex and risk status
Uptake of influenza vaccine increased with age and over time in both high- and low-risk groups. In high-risk groups the increase between 1989/90 and 2003/04 was similar in all age groups up to 34 years (5.2–6.5 per cent) after which the increase was more marked, especially among those aged 50–64 years and 65–74 years. In low-risk groups, no significant increase in uptake occurred until after the age of 50, within the study period (Table 1).
. | All ages . | . | 0–4 . | . | 5–9 . | . | 10–14 . | . | 15–19 . | . | 20–34 . | . | 35–49 . | . | 50–64 . | . | 65–74 . | . | 75+ . | . | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
. | N . | % . | n . | % . | n . | % . | N . | % . | N . | % . | n . | % . | N . | % . | n . | % . | n . | % . | N . | % . | ||||||||||
High risk | ||||||||||||||||||||||||||||||
89–90 | 9270 | 20.8 | 12 | 0.7 | 41 | 1.6 | 50 | 2.5 | 45 | 2.7 | 256 | 5.1 | 578 | 10.4 | 1978 | 22.0 | 2942 | 34.6 | 3368 | 38.7 | ||||||||||
90–91 | 30 285 | 21.8 | 21 | 0.4 | 100 | 1.2 | 157 | 2.3 | 148 | 2.8 | 676 | 4.3 | 1660 | 9.7 | 6095 | 22.8 | 9916 | 38.3 | 11 512 | 42.4 | ||||||||||
91–92 | 78 648 | 23.5 | 60 | 0.4 | 320 | 1.5 | 515 | 2.8 | 503 | 3.9 | 2260 | 5.6 | 4961 | 11.9 | 16 121 | 25.7 | 25 044 | 41.4 | 28 864 | 46.1 | ||||||||||
92–93 | 92 664 | 22.6 | 116 | 0.6 | 463 | 1.7 | 794 | 3.3 | 697 | 4.2 | 3041 | 5.9 | 6126 | 11.7 | 18 827 | 25.0 | 29 221 | 40.2 | 33 379 | 45.7 | ||||||||||
93–94 | 109 035 | 26.0 | 244 | 1.3 | 839 | 2.9 | 1192 | 4.4 | 1112 | 6.1 | 4095 | 7.6 | 7903 | 14.4 | 22 775 | 30.0 | 34 536 | 47.8 | 36 339 | 51.6 | ||||||||||
94–95 | 114 613 | 25.9 | 205 | 1.1 | 853 | 2.7 | 1228 | 4.2 | 1173 | 5.6 | 4265 | 7.4 | 8305 | 14.2 | 23 725 | 30.0 | 36 177 | 48.7 | 38 682 | 53.9 | ||||||||||
95–96 | 99 588 | 26.3 | 156 | 1.0 | 736 | 2.6 | 1141 | 4.4 | 1162 | 6.1 | 3969 | 8.1 | 7689 | 15.0 | 21 016 | 31.2 | 30 185 | 49.4 | 33 534 | 55.0 | ||||||||||
96–97 | 85 136 | 25.8 | 178 | 1.5 | 719 | 3.0 | 1041 | 4.5 | 997 | 5.6 | 3195 | 7.5 | 6559 | 14.5 | 18 123 | 30.5 | 25 412 | 48.7 | 28 912 | 53.5 | ||||||||||
97–98 | 82 822 | 28.6 | 167 | 1.7 | 695 | 3.3 | 991 | 4.8 | 996 | 6.1 | 3191 | 8.5 | 6540 | 16.5 | 18 186 | 34.4 | 24 423 | 54.6 | 27 633 | 59.2 | ||||||||||
98–99 | 63 945 | 30.0 | 109 | 1.6 | 462 | 3.0 | 729 | 4.5 | 639 | 4.8 | 2258 | 7.8 | 4819 | 15.5 | 14 117 | 33.2 | 18 610 | 53.5 | 22 202 | 48.6 | ||||||||||
99–00 | 116 442 | 29.4 | 225 | 2.4 | 860 | 3.5 | 1293 | 4.7 | 1209 | 5.3 | 3991 | 7.6 | 9164 | 15.9 | 25 730 | 33.8 | 34 040 | 55.8 | 75 439 | 53.2 | ||||||||||
65+ | ||||||||||||||||||||||||||||||
N | % | |||||||||||||||||||||||||||||
High risk | ||||||||||||||||||||||||||||||
00–01 | 143 034 | 36.9 | 216 | 2.7 | 943 | 4.2 | 1411 | 5.3 | 1289 | 5.7 | 4807 | 9.3 | 11 018 | 19.1 | 30 745 | 40.8 | 193 186 | 65.8 | ** | ** | ||||||||||
01–02 | 134 977 | 38.4 | 163 | 2.5 | 777 | 4.2 | 1210 | 5.1 | 1250 | 6.0 | 4395 | 9.6 | 10 292 | 19.9 | 29 152 | 42.1 | 185 039 | 67.5 | ** | ** | ||||||||||
02–03 | 110 336 | 39.5 | 117 | 2.6 | 559 | 4.1 | 935 | 5.0 | 963 | 5.7 | 3422 | 9.3 | 8556 | 20.4 | 24 060 | 43.5 | 150 186 | 69.4 | ** | ** | ||||||||||
03–04 | 149 311 | 42.5 | 295 | 6.1 | 1201 | 7.7 | 1783 | 7.7 | 1688 | 7.7 | 5397 | 11.4 | 12786 | 23.8 | 33 385 | 47.7 | 194 703 | 72.1 | ** | ** | ||||||||||
All ages | 0–4 | 5–9 | 10–14 | 15–19 | 20–34 | 35–49 | 50–64 | 65–74 | 75+ | |||||||||||||||||||||
N | % | n | % | N | % | n | % | N | % | n | % | N | % | N | % | N | % | N | % | |||||||||||
Low risk | ||||||||||||||||||||||||||||||
89–90 | 12 734 | 4.3 | 13 | 0.1 | 68 | 0.3 | 296 | 1.8 | 224 | 1.2 | 738 | 1.0 | 1412 | 2.1 | 2664 | 5.9 | 3950 | 17.0 | 3369 | 20.8 | ||||||||||
90–91 | 38 590 | 4.4 | 26 | 0.0 | 124 | 0.2 | 438 | 0.8 | 434 | 0.8 | 1730 | 0.8 | 3719 | 1.8 | 8290 | 6.2 | 12 757 | 19.1 | 11 072 | 24.0 | ||||||||||
91–92 | 96 163 | 4.8 | 62 | 0.0 | 258 | 0.2 | 752 | 0.6 | 924 | 0.8 | 5057 | 1.0 | 10 494 | 2.2 | 20 892 | 6.9 | 31 020 | 20.8 | 26 704 | 25.7 | ||||||||||
92–93 | 104 383 | 4.6 | 71 | 0.1 | 255 | 0.2 | 772 | 0.6 | 982 | 0.8 | 5458 | 1.0 | 11 436 | 2.1 | 22 722 | 6.6 | 33 686 | 20.0 | 29 001 | 25.4 | ||||||||||
93–94 | 118 319 | 5.5 | 122 | 0.1 | 334 | 0.2 | 808 | 0.6 | 1026 | 0.4 | 6064 | 1.2 | 13 026 | 2.6 | 26 282 | 7.9 | 39 652 | 25.0 | 31 005 | 29.9 | ||||||||||
94–95 | 114 126 | 5.4 | 97 | 0.1 | 260 | 0.2 | 720 | 0.5 | 820 | 0.7 | 5271 | 1.1 | 11 739 | 2.3 | 25 298 | 7.5 | 38 748 | 24.9 | 31 173 | 30.7 | ||||||||||
95–96 | 93 699 | 5.6 | 66 | 0.1 | 228 | 0.2 | 724 | 0.7 | 776 | 0.9 | 4370 | 1.1 | 9722 | 2.4 | 20 592 | 7.6 | 30 430 | 25.1 | 26 791 | 32.4 | ||||||||||
96–97 | 75 560 | 5.4 | 72 | 0.1 | 210 | 0.2 | 585 | 0.7 | 657 | 0.9 | 3066 | 1.0 | 7357 | 2.2 | 16 666 | 7.2 | 24 776 | 25.2 | 22 171 | 31.8 | ||||||||||
97–98 | 72 982 | 6.3 | 68 | 0.1 | 188 | 0.2 | 466 | 0.6 | 652 | 1.0 | 3124 | 1.2 | 7132 | 2.6 | 16 884 | 8.5 | 23 729 | 29.5 | 20 739 | 35.7 | ||||||||||
98–99 | 36 135 | 4.3 | 64 | 0.1 | 175 | 0.3 | 343 | 0.6 | 407 | 0.8 | 1963 | 1.0 | 4827 | 2.3 | 11 848 | 7.7 | 16 508 | 27.7 | ** | ** | ||||||||||
99–00 | 100 885 | 6.7 | 104 | 0.1 | 188 | 0.2 | 506 | 0.5 | 656 | 0.8 | 2958 | 0.9 | 8084 | 2.2 | 21 797 | 8.0 | 31 083 | 30.6 | ** | ** | ||||||||||
00–01 | 138 829 | 9.6 | 109 | 0.1 | 186 | 0.2 | 467 | 0.5 | 680 | 0.8 | 3063 | 1.0 | 8793 | 2.5 | 24 950 | 9.5 | ** | ** | ** | ** | ||||||||||
01–02 | 132 385 | 10.0 | 114 | 0.2 | 218 | 0.3 | 501 | 0.6 | 523 | 0.7 | 2709 | 1.0 | 7987 | 2.4 | 23 032 | 9.4 | ** | ** | ** | ** | ||||||||||
02–03 | 106 694 | 10.2 | 73 | 0.1 | 159 | 0.2 | 503 | 0.7 | 509 | 0.8 | 1982 | 0.9 | 6286 | 2.4 | 18 720 | 9.6 | ** | ** | ** | ** | ||||||||||
03–04* | 139 265 | 10.8 | 235 | 0.3 | 356 | 0.4 | 614 | 0.7 | 614 | 0.8 | 2600 | 1.0 | 8307 | 2.6 | 24 612 | 10.1 | ** | ** | ** | ** |
. | All ages . | . | 0–4 . | . | 5–9 . | . | 10–14 . | . | 15–19 . | . | 20–34 . | . | 35–49 . | . | 50–64 . | . | 65–74 . | . | 75+ . | . | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
. | N . | % . | n . | % . | n . | % . | N . | % . | N . | % . | n . | % . | N . | % . | n . | % . | n . | % . | N . | % . | ||||||||||
High risk | ||||||||||||||||||||||||||||||
89–90 | 9270 | 20.8 | 12 | 0.7 | 41 | 1.6 | 50 | 2.5 | 45 | 2.7 | 256 | 5.1 | 578 | 10.4 | 1978 | 22.0 | 2942 | 34.6 | 3368 | 38.7 | ||||||||||
90–91 | 30 285 | 21.8 | 21 | 0.4 | 100 | 1.2 | 157 | 2.3 | 148 | 2.8 | 676 | 4.3 | 1660 | 9.7 | 6095 | 22.8 | 9916 | 38.3 | 11 512 | 42.4 | ||||||||||
91–92 | 78 648 | 23.5 | 60 | 0.4 | 320 | 1.5 | 515 | 2.8 | 503 | 3.9 | 2260 | 5.6 | 4961 | 11.9 | 16 121 | 25.7 | 25 044 | 41.4 | 28 864 | 46.1 | ||||||||||
92–93 | 92 664 | 22.6 | 116 | 0.6 | 463 | 1.7 | 794 | 3.3 | 697 | 4.2 | 3041 | 5.9 | 6126 | 11.7 | 18 827 | 25.0 | 29 221 | 40.2 | 33 379 | 45.7 | ||||||||||
93–94 | 109 035 | 26.0 | 244 | 1.3 | 839 | 2.9 | 1192 | 4.4 | 1112 | 6.1 | 4095 | 7.6 | 7903 | 14.4 | 22 775 | 30.0 | 34 536 | 47.8 | 36 339 | 51.6 | ||||||||||
94–95 | 114 613 | 25.9 | 205 | 1.1 | 853 | 2.7 | 1228 | 4.2 | 1173 | 5.6 | 4265 | 7.4 | 8305 | 14.2 | 23 725 | 30.0 | 36 177 | 48.7 | 38 682 | 53.9 | ||||||||||
95–96 | 99 588 | 26.3 | 156 | 1.0 | 736 | 2.6 | 1141 | 4.4 | 1162 | 6.1 | 3969 | 8.1 | 7689 | 15.0 | 21 016 | 31.2 | 30 185 | 49.4 | 33 534 | 55.0 | ||||||||||
96–97 | 85 136 | 25.8 | 178 | 1.5 | 719 | 3.0 | 1041 | 4.5 | 997 | 5.6 | 3195 | 7.5 | 6559 | 14.5 | 18 123 | 30.5 | 25 412 | 48.7 | 28 912 | 53.5 | ||||||||||
97–98 | 82 822 | 28.6 | 167 | 1.7 | 695 | 3.3 | 991 | 4.8 | 996 | 6.1 | 3191 | 8.5 | 6540 | 16.5 | 18 186 | 34.4 | 24 423 | 54.6 | 27 633 | 59.2 | ||||||||||
98–99 | 63 945 | 30.0 | 109 | 1.6 | 462 | 3.0 | 729 | 4.5 | 639 | 4.8 | 2258 | 7.8 | 4819 | 15.5 | 14 117 | 33.2 | 18 610 | 53.5 | 22 202 | 48.6 | ||||||||||
99–00 | 116 442 | 29.4 | 225 | 2.4 | 860 | 3.5 | 1293 | 4.7 | 1209 | 5.3 | 3991 | 7.6 | 9164 | 15.9 | 25 730 | 33.8 | 34 040 | 55.8 | 75 439 | 53.2 | ||||||||||
65+ | ||||||||||||||||||||||||||||||
N | % | |||||||||||||||||||||||||||||
High risk | ||||||||||||||||||||||||||||||
00–01 | 143 034 | 36.9 | 216 | 2.7 | 943 | 4.2 | 1411 | 5.3 | 1289 | 5.7 | 4807 | 9.3 | 11 018 | 19.1 | 30 745 | 40.8 | 193 186 | 65.8 | ** | ** | ||||||||||
01–02 | 134 977 | 38.4 | 163 | 2.5 | 777 | 4.2 | 1210 | 5.1 | 1250 | 6.0 | 4395 | 9.6 | 10 292 | 19.9 | 29 152 | 42.1 | 185 039 | 67.5 | ** | ** | ||||||||||
02–03 | 110 336 | 39.5 | 117 | 2.6 | 559 | 4.1 | 935 | 5.0 | 963 | 5.7 | 3422 | 9.3 | 8556 | 20.4 | 24 060 | 43.5 | 150 186 | 69.4 | ** | ** | ||||||||||
03–04 | 149 311 | 42.5 | 295 | 6.1 | 1201 | 7.7 | 1783 | 7.7 | 1688 | 7.7 | 5397 | 11.4 | 12786 | 23.8 | 33 385 | 47.7 | 194 703 | 72.1 | ** | ** | ||||||||||
All ages | 0–4 | 5–9 | 10–14 | 15–19 | 20–34 | 35–49 | 50–64 | 65–74 | 75+ | |||||||||||||||||||||
N | % | n | % | N | % | n | % | N | % | n | % | N | % | N | % | N | % | N | % | |||||||||||
Low risk | ||||||||||||||||||||||||||||||
89–90 | 12 734 | 4.3 | 13 | 0.1 | 68 | 0.3 | 296 | 1.8 | 224 | 1.2 | 738 | 1.0 | 1412 | 2.1 | 2664 | 5.9 | 3950 | 17.0 | 3369 | 20.8 | ||||||||||
90–91 | 38 590 | 4.4 | 26 | 0.0 | 124 | 0.2 | 438 | 0.8 | 434 | 0.8 | 1730 | 0.8 | 3719 | 1.8 | 8290 | 6.2 | 12 757 | 19.1 | 11 072 | 24.0 | ||||||||||
91–92 | 96 163 | 4.8 | 62 | 0.0 | 258 | 0.2 | 752 | 0.6 | 924 | 0.8 | 5057 | 1.0 | 10 494 | 2.2 | 20 892 | 6.9 | 31 020 | 20.8 | 26 704 | 25.7 | ||||||||||
92–93 | 104 383 | 4.6 | 71 | 0.1 | 255 | 0.2 | 772 | 0.6 | 982 | 0.8 | 5458 | 1.0 | 11 436 | 2.1 | 22 722 | 6.6 | 33 686 | 20.0 | 29 001 | 25.4 | ||||||||||
93–94 | 118 319 | 5.5 | 122 | 0.1 | 334 | 0.2 | 808 | 0.6 | 1026 | 0.4 | 6064 | 1.2 | 13 026 | 2.6 | 26 282 | 7.9 | 39 652 | 25.0 | 31 005 | 29.9 | ||||||||||
94–95 | 114 126 | 5.4 | 97 | 0.1 | 260 | 0.2 | 720 | 0.5 | 820 | 0.7 | 5271 | 1.1 | 11 739 | 2.3 | 25 298 | 7.5 | 38 748 | 24.9 | 31 173 | 30.7 | ||||||||||
95–96 | 93 699 | 5.6 | 66 | 0.1 | 228 | 0.2 | 724 | 0.7 | 776 | 0.9 | 4370 | 1.1 | 9722 | 2.4 | 20 592 | 7.6 | 30 430 | 25.1 | 26 791 | 32.4 | ||||||||||
96–97 | 75 560 | 5.4 | 72 | 0.1 | 210 | 0.2 | 585 | 0.7 | 657 | 0.9 | 3066 | 1.0 | 7357 | 2.2 | 16 666 | 7.2 | 24 776 | 25.2 | 22 171 | 31.8 | ||||||||||
97–98 | 72 982 | 6.3 | 68 | 0.1 | 188 | 0.2 | 466 | 0.6 | 652 | 1.0 | 3124 | 1.2 | 7132 | 2.6 | 16 884 | 8.5 | 23 729 | 29.5 | 20 739 | 35.7 | ||||||||||
98–99 | 36 135 | 4.3 | 64 | 0.1 | 175 | 0.3 | 343 | 0.6 | 407 | 0.8 | 1963 | 1.0 | 4827 | 2.3 | 11 848 | 7.7 | 16 508 | 27.7 | ** | ** | ||||||||||
99–00 | 100 885 | 6.7 | 104 | 0.1 | 188 | 0.2 | 506 | 0.5 | 656 | 0.8 | 2958 | 0.9 | 8084 | 2.2 | 21 797 | 8.0 | 31 083 | 30.6 | ** | ** | ||||||||||
00–01 | 138 829 | 9.6 | 109 | 0.1 | 186 | 0.2 | 467 | 0.5 | 680 | 0.8 | 3063 | 1.0 | 8793 | 2.5 | 24 950 | 9.5 | ** | ** | ** | ** | ||||||||||
01–02 | 132 385 | 10.0 | 114 | 0.2 | 218 | 0.3 | 501 | 0.6 | 523 | 0.7 | 2709 | 1.0 | 7987 | 2.4 | 23 032 | 9.4 | ** | ** | ** | ** | ||||||||||
02–03 | 106 694 | 10.2 | 73 | 0.1 | 159 | 0.2 | 503 | 0.7 | 509 | 0.8 | 1982 | 0.9 | 6286 | 2.4 | 18 720 | 9.6 | ** | ** | ** | ** | ||||||||||
03–04* | 139 265 | 10.8 | 235 | 0.3 | 356 | 0.4 | 614 | 0.7 | 614 | 0.8 | 2600 | 1.0 | 8307 | 2.6 | 24 612 | 10.1 | ** | ** | ** | ** |
. | All ages . | . | 0–4 . | . | 5–9 . | . | 10–14 . | . | 15–19 . | . | 20–34 . | . | 35–49 . | . | 50–64 . | . | 65–74 . | . | 75+ . | . | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
. | N . | % . | n . | % . | n . | % . | N . | % . | N . | % . | n . | % . | N . | % . | n . | % . | n . | % . | N . | % . | ||||||||||
High risk | ||||||||||||||||||||||||||||||
89–90 | 9270 | 20.8 | 12 | 0.7 | 41 | 1.6 | 50 | 2.5 | 45 | 2.7 | 256 | 5.1 | 578 | 10.4 | 1978 | 22.0 | 2942 | 34.6 | 3368 | 38.7 | ||||||||||
90–91 | 30 285 | 21.8 | 21 | 0.4 | 100 | 1.2 | 157 | 2.3 | 148 | 2.8 | 676 | 4.3 | 1660 | 9.7 | 6095 | 22.8 | 9916 | 38.3 | 11 512 | 42.4 | ||||||||||
91–92 | 78 648 | 23.5 | 60 | 0.4 | 320 | 1.5 | 515 | 2.8 | 503 | 3.9 | 2260 | 5.6 | 4961 | 11.9 | 16 121 | 25.7 | 25 044 | 41.4 | 28 864 | 46.1 | ||||||||||
92–93 | 92 664 | 22.6 | 116 | 0.6 | 463 | 1.7 | 794 | 3.3 | 697 | 4.2 | 3041 | 5.9 | 6126 | 11.7 | 18 827 | 25.0 | 29 221 | 40.2 | 33 379 | 45.7 | ||||||||||
93–94 | 109 035 | 26.0 | 244 | 1.3 | 839 | 2.9 | 1192 | 4.4 | 1112 | 6.1 | 4095 | 7.6 | 7903 | 14.4 | 22 775 | 30.0 | 34 536 | 47.8 | 36 339 | 51.6 | ||||||||||
94–95 | 114 613 | 25.9 | 205 | 1.1 | 853 | 2.7 | 1228 | 4.2 | 1173 | 5.6 | 4265 | 7.4 | 8305 | 14.2 | 23 725 | 30.0 | 36 177 | 48.7 | 38 682 | 53.9 | ||||||||||
95–96 | 99 588 | 26.3 | 156 | 1.0 | 736 | 2.6 | 1141 | 4.4 | 1162 | 6.1 | 3969 | 8.1 | 7689 | 15.0 | 21 016 | 31.2 | 30 185 | 49.4 | 33 534 | 55.0 | ||||||||||
96–97 | 85 136 | 25.8 | 178 | 1.5 | 719 | 3.0 | 1041 | 4.5 | 997 | 5.6 | 3195 | 7.5 | 6559 | 14.5 | 18 123 | 30.5 | 25 412 | 48.7 | 28 912 | 53.5 | ||||||||||
97–98 | 82 822 | 28.6 | 167 | 1.7 | 695 | 3.3 | 991 | 4.8 | 996 | 6.1 | 3191 | 8.5 | 6540 | 16.5 | 18 186 | 34.4 | 24 423 | 54.6 | 27 633 | 59.2 | ||||||||||
98–99 | 63 945 | 30.0 | 109 | 1.6 | 462 | 3.0 | 729 | 4.5 | 639 | 4.8 | 2258 | 7.8 | 4819 | 15.5 | 14 117 | 33.2 | 18 610 | 53.5 | 22 202 | 48.6 | ||||||||||
99–00 | 116 442 | 29.4 | 225 | 2.4 | 860 | 3.5 | 1293 | 4.7 | 1209 | 5.3 | 3991 | 7.6 | 9164 | 15.9 | 25 730 | 33.8 | 34 040 | 55.8 | 75 439 | 53.2 | ||||||||||
65+ | ||||||||||||||||||||||||||||||
N | % | |||||||||||||||||||||||||||||
High risk | ||||||||||||||||||||||||||||||
00–01 | 143 034 | 36.9 | 216 | 2.7 | 943 | 4.2 | 1411 | 5.3 | 1289 | 5.7 | 4807 | 9.3 | 11 018 | 19.1 | 30 745 | 40.8 | 193 186 | 65.8 | ** | ** | ||||||||||
01–02 | 134 977 | 38.4 | 163 | 2.5 | 777 | 4.2 | 1210 | 5.1 | 1250 | 6.0 | 4395 | 9.6 | 10 292 | 19.9 | 29 152 | 42.1 | 185 039 | 67.5 | ** | ** | ||||||||||
02–03 | 110 336 | 39.5 | 117 | 2.6 | 559 | 4.1 | 935 | 5.0 | 963 | 5.7 | 3422 | 9.3 | 8556 | 20.4 | 24 060 | 43.5 | 150 186 | 69.4 | ** | ** | ||||||||||
03–04 | 149 311 | 42.5 | 295 | 6.1 | 1201 | 7.7 | 1783 | 7.7 | 1688 | 7.7 | 5397 | 11.4 | 12786 | 23.8 | 33 385 | 47.7 | 194 703 | 72.1 | ** | ** | ||||||||||
All ages | 0–4 | 5–9 | 10–14 | 15–19 | 20–34 | 35–49 | 50–64 | 65–74 | 75+ | |||||||||||||||||||||
N | % | n | % | N | % | n | % | N | % | n | % | N | % | N | % | N | % | N | % | |||||||||||
Low risk | ||||||||||||||||||||||||||||||
89–90 | 12 734 | 4.3 | 13 | 0.1 | 68 | 0.3 | 296 | 1.8 | 224 | 1.2 | 738 | 1.0 | 1412 | 2.1 | 2664 | 5.9 | 3950 | 17.0 | 3369 | 20.8 | ||||||||||
90–91 | 38 590 | 4.4 | 26 | 0.0 | 124 | 0.2 | 438 | 0.8 | 434 | 0.8 | 1730 | 0.8 | 3719 | 1.8 | 8290 | 6.2 | 12 757 | 19.1 | 11 072 | 24.0 | ||||||||||
91–92 | 96 163 | 4.8 | 62 | 0.0 | 258 | 0.2 | 752 | 0.6 | 924 | 0.8 | 5057 | 1.0 | 10 494 | 2.2 | 20 892 | 6.9 | 31 020 | 20.8 | 26 704 | 25.7 | ||||||||||
92–93 | 104 383 | 4.6 | 71 | 0.1 | 255 | 0.2 | 772 | 0.6 | 982 | 0.8 | 5458 | 1.0 | 11 436 | 2.1 | 22 722 | 6.6 | 33 686 | 20.0 | 29 001 | 25.4 | ||||||||||
93–94 | 118 319 | 5.5 | 122 | 0.1 | 334 | 0.2 | 808 | 0.6 | 1026 | 0.4 | 6064 | 1.2 | 13 026 | 2.6 | 26 282 | 7.9 | 39 652 | 25.0 | 31 005 | 29.9 | ||||||||||
94–95 | 114 126 | 5.4 | 97 | 0.1 | 260 | 0.2 | 720 | 0.5 | 820 | 0.7 | 5271 | 1.1 | 11 739 | 2.3 | 25 298 | 7.5 | 38 748 | 24.9 | 31 173 | 30.7 | ||||||||||
95–96 | 93 699 | 5.6 | 66 | 0.1 | 228 | 0.2 | 724 | 0.7 | 776 | 0.9 | 4370 | 1.1 | 9722 | 2.4 | 20 592 | 7.6 | 30 430 | 25.1 | 26 791 | 32.4 | ||||||||||
96–97 | 75 560 | 5.4 | 72 | 0.1 | 210 | 0.2 | 585 | 0.7 | 657 | 0.9 | 3066 | 1.0 | 7357 | 2.2 | 16 666 | 7.2 | 24 776 | 25.2 | 22 171 | 31.8 | ||||||||||
97–98 | 72 982 | 6.3 | 68 | 0.1 | 188 | 0.2 | 466 | 0.6 | 652 | 1.0 | 3124 | 1.2 | 7132 | 2.6 | 16 884 | 8.5 | 23 729 | 29.5 | 20 739 | 35.7 | ||||||||||
98–99 | 36 135 | 4.3 | 64 | 0.1 | 175 | 0.3 | 343 | 0.6 | 407 | 0.8 | 1963 | 1.0 | 4827 | 2.3 | 11 848 | 7.7 | 16 508 | 27.7 | ** | ** | ||||||||||
99–00 | 100 885 | 6.7 | 104 | 0.1 | 188 | 0.2 | 506 | 0.5 | 656 | 0.8 | 2958 | 0.9 | 8084 | 2.2 | 21 797 | 8.0 | 31 083 | 30.6 | ** | ** | ||||||||||
00–01 | 138 829 | 9.6 | 109 | 0.1 | 186 | 0.2 | 467 | 0.5 | 680 | 0.8 | 3063 | 1.0 | 8793 | 2.5 | 24 950 | 9.5 | ** | ** | ** | ** | ||||||||||
01–02 | 132 385 | 10.0 | 114 | 0.2 | 218 | 0.3 | 501 | 0.6 | 523 | 0.7 | 2709 | 1.0 | 7987 | 2.4 | 23 032 | 9.4 | ** | ** | ** | ** | ||||||||||
02–03 | 106 694 | 10.2 | 73 | 0.1 | 159 | 0.2 | 503 | 0.7 | 509 | 0.8 | 1982 | 0.9 | 6286 | 2.4 | 18 720 | 9.6 | ** | ** | ** | ** | ||||||||||
03–04* | 139 265 | 10.8 | 235 | 0.3 | 356 | 0.4 | 614 | 0.7 | 614 | 0.8 | 2600 | 1.0 | 8307 | 2.6 | 24 612 | 10.1 | ** | ** | ** | ** |
. | All ages . | . | 0–4 . | . | 5–9 . | . | 10–14 . | . | 15–19 . | . | 20–34 . | . | 35–49 . | . | 50–64 . | . | 65–74 . | . | 75+ . | . | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
. | N . | % . | n . | % . | n . | % . | N . | % . | N . | % . | n . | % . | N . | % . | n . | % . | n . | % . | N . | % . | ||||||||||
High risk | ||||||||||||||||||||||||||||||
89–90 | 9270 | 20.8 | 12 | 0.7 | 41 | 1.6 | 50 | 2.5 | 45 | 2.7 | 256 | 5.1 | 578 | 10.4 | 1978 | 22.0 | 2942 | 34.6 | 3368 | 38.7 | ||||||||||
90–91 | 30 285 | 21.8 | 21 | 0.4 | 100 | 1.2 | 157 | 2.3 | 148 | 2.8 | 676 | 4.3 | 1660 | 9.7 | 6095 | 22.8 | 9916 | 38.3 | 11 512 | 42.4 | ||||||||||
91–92 | 78 648 | 23.5 | 60 | 0.4 | 320 | 1.5 | 515 | 2.8 | 503 | 3.9 | 2260 | 5.6 | 4961 | 11.9 | 16 121 | 25.7 | 25 044 | 41.4 | 28 864 | 46.1 | ||||||||||
92–93 | 92 664 | 22.6 | 116 | 0.6 | 463 | 1.7 | 794 | 3.3 | 697 | 4.2 | 3041 | 5.9 | 6126 | 11.7 | 18 827 | 25.0 | 29 221 | 40.2 | 33 379 | 45.7 | ||||||||||
93–94 | 109 035 | 26.0 | 244 | 1.3 | 839 | 2.9 | 1192 | 4.4 | 1112 | 6.1 | 4095 | 7.6 | 7903 | 14.4 | 22 775 | 30.0 | 34 536 | 47.8 | 36 339 | 51.6 | ||||||||||
94–95 | 114 613 | 25.9 | 205 | 1.1 | 853 | 2.7 | 1228 | 4.2 | 1173 | 5.6 | 4265 | 7.4 | 8305 | 14.2 | 23 725 | 30.0 | 36 177 | 48.7 | 38 682 | 53.9 | ||||||||||
95–96 | 99 588 | 26.3 | 156 | 1.0 | 736 | 2.6 | 1141 | 4.4 | 1162 | 6.1 | 3969 | 8.1 | 7689 | 15.0 | 21 016 | 31.2 | 30 185 | 49.4 | 33 534 | 55.0 | ||||||||||
96–97 | 85 136 | 25.8 | 178 | 1.5 | 719 | 3.0 | 1041 | 4.5 | 997 | 5.6 | 3195 | 7.5 | 6559 | 14.5 | 18 123 | 30.5 | 25 412 | 48.7 | 28 912 | 53.5 | ||||||||||
97–98 | 82 822 | 28.6 | 167 | 1.7 | 695 | 3.3 | 991 | 4.8 | 996 | 6.1 | 3191 | 8.5 | 6540 | 16.5 | 18 186 | 34.4 | 24 423 | 54.6 | 27 633 | 59.2 | ||||||||||
98–99 | 63 945 | 30.0 | 109 | 1.6 | 462 | 3.0 | 729 | 4.5 | 639 | 4.8 | 2258 | 7.8 | 4819 | 15.5 | 14 117 | 33.2 | 18 610 | 53.5 | 22 202 | 48.6 | ||||||||||
99–00 | 116 442 | 29.4 | 225 | 2.4 | 860 | 3.5 | 1293 | 4.7 | 1209 | 5.3 | 3991 | 7.6 | 9164 | 15.9 | 25 730 | 33.8 | 34 040 | 55.8 | 75 439 | 53.2 | ||||||||||
65+ | ||||||||||||||||||||||||||||||
N | % | |||||||||||||||||||||||||||||
High risk | ||||||||||||||||||||||||||||||
00–01 | 143 034 | 36.9 | 216 | 2.7 | 943 | 4.2 | 1411 | 5.3 | 1289 | 5.7 | 4807 | 9.3 | 11 018 | 19.1 | 30 745 | 40.8 | 193 186 | 65.8 | ** | ** | ||||||||||
01–02 | 134 977 | 38.4 | 163 | 2.5 | 777 | 4.2 | 1210 | 5.1 | 1250 | 6.0 | 4395 | 9.6 | 10 292 | 19.9 | 29 152 | 42.1 | 185 039 | 67.5 | ** | ** | ||||||||||
02–03 | 110 336 | 39.5 | 117 | 2.6 | 559 | 4.1 | 935 | 5.0 | 963 | 5.7 | 3422 | 9.3 | 8556 | 20.4 | 24 060 | 43.5 | 150 186 | 69.4 | ** | ** | ||||||||||
03–04 | 149 311 | 42.5 | 295 | 6.1 | 1201 | 7.7 | 1783 | 7.7 | 1688 | 7.7 | 5397 | 11.4 | 12786 | 23.8 | 33 385 | 47.7 | 194 703 | 72.1 | ** | ** | ||||||||||
All ages | 0–4 | 5–9 | 10–14 | 15–19 | 20–34 | 35–49 | 50–64 | 65–74 | 75+ | |||||||||||||||||||||
N | % | n | % | N | % | n | % | N | % | n | % | N | % | N | % | N | % | N | % | |||||||||||
Low risk | ||||||||||||||||||||||||||||||
89–90 | 12 734 | 4.3 | 13 | 0.1 | 68 | 0.3 | 296 | 1.8 | 224 | 1.2 | 738 | 1.0 | 1412 | 2.1 | 2664 | 5.9 | 3950 | 17.0 | 3369 | 20.8 | ||||||||||
90–91 | 38 590 | 4.4 | 26 | 0.0 | 124 | 0.2 | 438 | 0.8 | 434 | 0.8 | 1730 | 0.8 | 3719 | 1.8 | 8290 | 6.2 | 12 757 | 19.1 | 11 072 | 24.0 | ||||||||||
91–92 | 96 163 | 4.8 | 62 | 0.0 | 258 | 0.2 | 752 | 0.6 | 924 | 0.8 | 5057 | 1.0 | 10 494 | 2.2 | 20 892 | 6.9 | 31 020 | 20.8 | 26 704 | 25.7 | ||||||||||
92–93 | 104 383 | 4.6 | 71 | 0.1 | 255 | 0.2 | 772 | 0.6 | 982 | 0.8 | 5458 | 1.0 | 11 436 | 2.1 | 22 722 | 6.6 | 33 686 | 20.0 | 29 001 | 25.4 | ||||||||||
93–94 | 118 319 | 5.5 | 122 | 0.1 | 334 | 0.2 | 808 | 0.6 | 1026 | 0.4 | 6064 | 1.2 | 13 026 | 2.6 | 26 282 | 7.9 | 39 652 | 25.0 | 31 005 | 29.9 | ||||||||||
94–95 | 114 126 | 5.4 | 97 | 0.1 | 260 | 0.2 | 720 | 0.5 | 820 | 0.7 | 5271 | 1.1 | 11 739 | 2.3 | 25 298 | 7.5 | 38 748 | 24.9 | 31 173 | 30.7 | ||||||||||
95–96 | 93 699 | 5.6 | 66 | 0.1 | 228 | 0.2 | 724 | 0.7 | 776 | 0.9 | 4370 | 1.1 | 9722 | 2.4 | 20 592 | 7.6 | 30 430 | 25.1 | 26 791 | 32.4 | ||||||||||
96–97 | 75 560 | 5.4 | 72 | 0.1 | 210 | 0.2 | 585 | 0.7 | 657 | 0.9 | 3066 | 1.0 | 7357 | 2.2 | 16 666 | 7.2 | 24 776 | 25.2 | 22 171 | 31.8 | ||||||||||
97–98 | 72 982 | 6.3 | 68 | 0.1 | 188 | 0.2 | 466 | 0.6 | 652 | 1.0 | 3124 | 1.2 | 7132 | 2.6 | 16 884 | 8.5 | 23 729 | 29.5 | 20 739 | 35.7 | ||||||||||
98–99 | 36 135 | 4.3 | 64 | 0.1 | 175 | 0.3 | 343 | 0.6 | 407 | 0.8 | 1963 | 1.0 | 4827 | 2.3 | 11 848 | 7.7 | 16 508 | 27.7 | ** | ** | ||||||||||
99–00 | 100 885 | 6.7 | 104 | 0.1 | 188 | 0.2 | 506 | 0.5 | 656 | 0.8 | 2958 | 0.9 | 8084 | 2.2 | 21 797 | 8.0 | 31 083 | 30.6 | ** | ** | ||||||||||
00–01 | 138 829 | 9.6 | 109 | 0.1 | 186 | 0.2 | 467 | 0.5 | 680 | 0.8 | 3063 | 1.0 | 8793 | 2.5 | 24 950 | 9.5 | ** | ** | ** | ** | ||||||||||
01–02 | 132 385 | 10.0 | 114 | 0.2 | 218 | 0.3 | 501 | 0.6 | 523 | 0.7 | 2709 | 1.0 | 7987 | 2.4 | 23 032 | 9.4 | ** | ** | ** | ** | ||||||||||
02–03 | 106 694 | 10.2 | 73 | 0.1 | 159 | 0.2 | 503 | 0.7 | 509 | 0.8 | 1982 | 0.9 | 6286 | 2.4 | 18 720 | 9.6 | ** | ** | ** | ** | ||||||||||
03–04* | 139 265 | 10.8 | 235 | 0.3 | 356 | 0.4 | 614 | 0.7 | 614 | 0.8 | 2600 | 1.0 | 8307 | 2.6 | 24 612 | 10.1 | ** | ** | ** | ** |
In high-risk patients aged less than 65, the uptake ranged from 10.8 per cent in 1989/90 to 24.3 per cent in 2003/04. In patients aged 65 or more uptake reached 72.1 per cent in 2003/04. In low-risk patients aged 65 or more the uptake rate was 18.6 per cent in 1989/90 and 37.3 per cent in 1999/2000; the final year vaccination was administered according to clinical risk alone in this group. Until 1998/99 when policy for patients aged 75 or more changed, this age group had a higher uptake than all other age groups in both the high- and low-risk groups (Table 1).
There were significant differences between genders in uptake rates with those for females exceeding those for males for every age group up to 50–64 years for both high- and low-risk groups separately. After that, rates between the sexes were similar, irrespective of risk (Fig. 1).
The average annual changes in uptake obtained from modelling a linear trend over time by risk status, age group and sex showed greater increases occurring in the higher age groups (Table 2).
. | High risk . | No risk . |
---|---|---|
Age group* | ||
0–19 | 0.30 (0.25–0.36) | ± |
20–34 | 0.38 (0.24–0.52) | –0.00 (–0.02–0.02) |
35–49 | 0.83 (0.63–1.03) | 0.03 (–0.02–0.08) |
50–64 | 1.66 (1.41–1.91) | 0.27 (0.08–0.46) |
65–74 | 2.40 (2.22–2.59) | 1.25 (0.89–1.60) |
75 and over | 2.30 (1.85–2.74) | 1.69 (1.41–1.97) |
Sex† | ||
Male | 1.34 (1.11–1.57) | 0.22 (0.11–0.33) |
Female | 1.29 (1.08–1.50) | 0.28 (0.15–0.40) |
Overall | 1.31 (1.15–1.47) | 0.25 (0.16–0.34) |
. | High risk . | No risk . |
---|---|---|
Age group* | ||
0–19 | 0.30 (0.25–0.36) | ± |
20–34 | 0.38 (0.24–0.52) | –0.00 (–0.02–0.02) |
35–49 | 0.83 (0.63–1.03) | 0.03 (–0.02–0.08) |
50–64 | 1.66 (1.41–1.91) | 0.27 (0.08–0.46) |
65–74 | 2.40 (2.22–2.59) | 1.25 (0.89–1.60) |
75 and over | 2.30 (1.85–2.74) | 1.69 (1.41–1.97) |
Sex† | ||
Male | 1.34 (1.11–1.57) | 0.22 (0.11–0.33) |
Female | 1.29 (1.08–1.50) | 0.28 (0.15–0.40) |
Overall | 1.31 (1.15–1.47) | 0.25 (0.16–0.34) |
Averaged over males and females.
Averaged over age groups.
. | High risk . | No risk . |
---|---|---|
Age group* | ||
0–19 | 0.30 (0.25–0.36) | ± |
20–34 | 0.38 (0.24–0.52) | –0.00 (–0.02–0.02) |
35–49 | 0.83 (0.63–1.03) | 0.03 (–0.02–0.08) |
50–64 | 1.66 (1.41–1.91) | 0.27 (0.08–0.46) |
65–74 | 2.40 (2.22–2.59) | 1.25 (0.89–1.60) |
75 and over | 2.30 (1.85–2.74) | 1.69 (1.41–1.97) |
Sex† | ||
Male | 1.34 (1.11–1.57) | 0.22 (0.11–0.33) |
Female | 1.29 (1.08–1.50) | 0.28 (0.15–0.40) |
Overall | 1.31 (1.15–1.47) | 0.25 (0.16–0.34) |
. | High risk . | No risk . |
---|---|---|
Age group* | ||
0–19 | 0.30 (0.25–0.36) | ± |
20–34 | 0.38 (0.24–0.52) | –0.00 (–0.02–0.02) |
35–49 | 0.83 (0.63–1.03) | 0.03 (–0.02–0.08) |
50–64 | 1.66 (1.41–1.91) | 0.27 (0.08–0.46) |
65–74 | 2.40 (2.22–2.59) | 1.25 (0.89–1.60) |
75 and over | 2.30 (1.85–2.74) | 1.69 (1.41–1.97) |
Sex† | ||
Male | 1.34 (1.11–1.57) | 0.22 (0.11–0.33) |
Female | 1.29 (1.08–1.50) | 0.28 (0.15–0.40) |
Overall | 1.31 (1.15–1.47) | 0.25 (0.16–0.34) |
Averaged over males and females.
Averaged over age groups.
Month of vaccination
In each of the study years between 1989/90 and 1999/2000 most of the vaccines were administered in October, with an increasing proportion given in that month compared to November and December each year throughout the study period. However, in every month between October and January each year, high-risk patients aged 65 or more always had a higher cumulative uptake rate compared to the under 65 high risk. This was particularly evident each October when differences in cumulative uptake were as much as 9 per cent between the two groups (range 4.5–9.2 per cent), with mean percentage differences (95% CI) 7.25 (6.34–8.15), 4.58 (3.26–5.91) and 1.38 (0.86–1.90) and in each case p < 0.001. Vaccine administration had not been completed by the end of December in any of the study years, the worst year being 1991/92, when 94 per cent of all vaccines administered had been given by the end of December to high risk under 65 and 96.7 per cent to the 65 and over (Fig. 2).
Comparison with national data from DH vaccine uptake monitoring programme
Following the change in vaccination policy for the 65 and over in 2000, a national uptake target was set for this group by the DH. Evaluation of the policy has taken place through national monitoring and shows the national target has been reached annually from 2001/02. In 2003/04 when the target was 70 per cent, 71 per cent of all patients aged 65 years or more were vaccinated against influenza.8 A paired t test of no difference in means of GPRD against national data gave a result of p = 0.28 [with mean difference 0.47 per cent (95% CI = –0.65–1.58)], with GPRD having a slightly higher mean (Fig. 3).
Discussion
Main findings of this study
The publication of GPRD data in 1998 showed very low vaccine uptake in the high-risk population of people aged under 65, particularly in the youngest age groups. The updated data show that despite a limited increase in uptake, this group continues to remain seriously unprotected from influenza-related morbidity and mortality. In 2003/04, uptake was only 8 per cent overall in the high risk aged 0–19 and between 11 and 24 per cent in the high risk aged 20–49. It is only when people move into the 50–64 year age group that increases in uptake show an improvement over time. This age group is already the subject of immunization on an age basis rather than a risk basis in some countries, e.g. United States of America since 2000,9 on the grounds that many have a high-risk condition of which they are unaware and do not therefore appear in the at-risk denominator or actively seek vaccination. Lowering the age-related policy to 50 years in United Kingdom would increase the number that would benefit from immunization in this age group and would help to raise the absolute effectiveness of the recommendation by increasing uptake in all susceptible people, especially if uptake targets were set in line with those for the 65 and over.
What is already known on this topic
Increasing vaccine uptake is a key public health objective in most countries, particularly among the elderly and those in younger age groups with clinical conditions that put them at risk from the complications of influenza. Various local and sentinel studies in the 1990s showed uptake to be poor in United Kingdom and that less than half of those who required vaccine received it while as much as half of the vaccine was given to people of low risk.10–12 It was not until GPRD data became available in the mid-1990s that validated and nationally representative data in England and Wales could be used to determine vaccine uptake trends across all age and risk groups over time.
Several countries now have health promotion campaigns aimed at increasing vaccination coverage of high-risk patients, perhaps the most successful being the Netherlands where an impressive uptake rate of 70 per cent has been achieved in this group.13 In Canada universal annual immunization for all people above six months was introduced in 2004,14 and in United States of America in the same year universal immunization was recommended for children aged six months to two years to raise uptake.15 United Kingdom is not currently supporting an inclusive policy such as this but DH publicity for the influenza vaccination programme has recently given more prominence to recommending that people in the younger high-risk groups are vaccinated. High-risk patients need to be targeted in the same way that the elderly are recalled each year for vaccination.
What this study adds
This study has shown that base line data at the national level with trends over time are essential for providing evidence-based public health policy. It has also highlighted behavioural differences between vaccinated risk groups with high-risk patients aged 65 or more receiving vaccine earlier each season than those vaccinated in the under 65 high-risk group. Whether this was a self-selection process by the elderly because of their greater awareness of the annual immunization schedule or a prioritization process of patient groups by GPs is unknown. However, high-risk groups should be encouraged to receive vaccine as early as possible in the winter period. On average 40% of those high-risk patients who were eventually vaccinated between 1989/90 and 1999/2000 remained unvaccinated at the beginning of November each year. Influenza occurred very early in the years 1993/94 and 1995/96, resulting in a large proportion of those high-risk persons who were eventually vaccinated, unprotected during peak influenza activity.
Vaccine uptake appears to be unrelated to levels of influenza activity in the current or previous study year and has only increased when new vaccination policy has been introduced, accompanied by payments to GPs for administering the vaccine. This strategy has been successful for the elderly, most of whom are now vaccinated each year. In 2003, the DH announced that payments were also to be offered to GPs for vaccinating the under 65s at high risk.16 In 2004, national monitoring of uptake in this group began17 using monthly uptake data, again to enable targeting of areas with low uptake during the season and to provide evidence of effectiveness of the programme. It is anticipated that uptake rates in the younger high-risk patients will now increase, as this programme gets established.
One of the strengths of the GPRD data is that the selection of numerators and denominators for vaccine uptake is made from a complete data set of patient records. GPRD collects medical records for all registered patients from a representative sample of practices throughout United Kingdom and internally validates them based on the number of clinical, therapy and referral events within a practice. In contrast, the new DH national programme for monitoring vaccine uptake in the <65 years at high risk,17 uses denominator and numerator data submitted by individual GPs that may or may not have been validated at the practice level. This method of data collection is likely to result in inconsistent denominator rates caused by differences in allocation of risk codes to individual patient records from different practices. Thus uptake rates in the new national programme may be less reliable than those of the GPRD because of the lack of control over selection of patients included from the recognized risk groups. GPRD data will therefore continue to be an important comparative data set for the foreseeable future and until the national data is fully validated.
The young high-risk population remains the group least protected by influenza vaccine. Introducing age-related policies for the 65s and over has been extremely successful in raising their uptake rates. It now behoves the UK government to examine the evidence for lowering universal vaccination to people aged 50–64 and novel ways to increase uptake in children and young adults.
Limitations of this study
The number of practices providing data in the GPRD scheme varied over time. This may have affected the data’s representativeness, particularly at the beginning and towards the end of the study period when fewer practices participated.
Acknowledgements
The GPRD was set up in 1987 by VAMP Health Ltd. to collect pharmaco-epidemiological information from a sample of GP records. Since then the database has been managed by a series of government agencies. It was validated as a surveillance tool by the Office for National Statistics in 1994 and passed to the Medicines and Healthcare products Regulatory Agency (MHRA) for further development and management in 1999. We are grateful to ONS and MHRA for preparation of data and the Department of Health for funding the purchase of the data for this study. We are also grateful to Gagori Bandopadhyay for administrative support of the updated data and to Suzanne Elgohari for preparation of the 65s and over uptake data in the DH national monitoring scheme.
References
Department of Health. Major changes to the policy on influenza immunisation. CMO’s Update 26 May 2000.
Centers for Disease Control and Prevention. Prevention and control of influenza: recommendations of the Advisory Committee on Immunisation ractices (ACIP).
Public Health Agency of Canada. Statement on influenza vaccination for the 2004–2005 season.
Centers for Disease Control and Prevention. Prevention and control of influenza: recommendations of the Advisory Committee on Immunisation Practices (ACIP).
Department of Health. Influenza immunisation: item of service payments for at risk groups. CMO’s Update 18 September 2003.