Uptake of pertussis and influenza vaccination in pregnant women in Wales

Transcription

1 Vaccine Preventable Disease Programme Uptake of pertussis and influenza vaccination in pregnant women in Wales Authors: Anne McGowan, Richard Lewis, Richard Roberts, Simon Cottrell. Vaccine Preventable Disease Programme,. Date: 11th March 2014 Publication/ Distribution: Health Boards Welsh Government NHS Intranet Review Date: n/a Purpose and Summary of Document: Version: v2a Our aim was to estimate uptake of pertussis and influenza vaccine at the time of delivery. The survey was conducted in January The main findings were that 69.3% of pregnant women reported that they received pertussis vaccination, 70.5% of pregnant women reported that they received influenza vaccination, 61.9% of pregnant women reported that they received both pertussis and influenza vaccination, and 4 in 5 women recalled being offered the vaccines during pregnancy. Compared with uptakes last year there has been 5.9% increase in pertussis and an 8.9% increase in influenza uptakes. Work Plan reference: VPDP Date: March 2014 Version:v2 Page: 1 of 19

2 CONTENTS Background... 3 Introduction... 3 Vaccination of pregnant women... 3 Measuring vaccine uptake in pregnant women using Audit Point of delivery surveillance survey... 5 Methodology... 5 Results... 5 Pertussis Vaccine... 6 Influenza vaccine Pertussis and Influenza vaccine Conclusions Acknowledgement References Appendices Date: March 2014 Version:v2 Page: 2 of 19

3 Background Following a rise in the number of cases of whooping cough in young babies during 2012, the Chief Medical Officer for Wales announced on 28 th September 2012 that pregnant women will be offered vaccination to protect their newborn babies. An extension to the programme was confirmed by the CMO in April A survey was conducted between January 20 th and January 24 th 2014 in all the main maternity units in Wales to estimate the uptake of pertussis vaccine in pregnant women at the time of delivery. At the same time, uptake of influenza vaccine was also surveyed. Introduction Pertussis typically has a cyclical incidence with peaks of cases every three to four years. The previous peak in England and Wales was in 2008, with 902 laboratory confirmed cases (HPA, 2012). In 2012 there was a significant increase in cases of pertussis in the UK. In Wales, there were 343 confirmed cases in 2012, 29 in infants under one year of age, 22 aged under 3 months. There have been 150 confirmed cases reported in 2013 up to 31 st July 2013 (PHW, 2014). The youngest children are the group most susceptible to complications. There have also been increased numbers reported in other countries, including the USA, Australia, New Zealand and Canada. (England and Wales, Kimietowicz 2012; USA, Winter et al 2012; Australia, Australian Government; Canada, Fisman et al 2011). Vaccination of pregnant women The Joint Committee on Vaccination and Immunisation (JCVI) reviewed the available information on the evolving outbreak in August 2012 and recommended that the best way to protect young infants before they are old enough to start their primary immunisations was to offer pertussis vaccination to pregnant women between weeks gestation (JCVI 2012). Vaccination of the mother boosts maternal antibodies that can pass across the placenta to the unborn infant to provide protection during the early weeks of life. The benefits of influenza vaccine for pregnant women are now well established. All pregnant women are recommended to receive influenza vaccine irrespective of their stage of pregnancy. 1 Date: March 2014 Version: 2 Page: 3 of 19

4 Measuring vaccine uptake in pregnant women using Audit+ monitors uptake of influenza immunisation in pregnant women using data collected by General Practices through Audit+. There are challenges in collecting and reporting immunisation uptake data for influenza and pertussis, which highlights the importance of surveying the number of women giving birth who have been vaccinated. Influenza immunisation uptake data collected through Audit+ includes all women who were recorded as being pregnant as at the start of September 2013 or who were newly recorded as being pregnant between September 2013 and January As a result, the denominator will include a proportion of women whose pregnancies ended before they would have been offered the vaccine. The current estimated uptake through Audit+ data as of 19th February for influenza is 42.3% for Wales, ranging from 31.9% % between health boards (PHW 2014). Pertussis immunisation is offered to women in their third trimester of pregnancy; it was not possible to identify this group of women using Audit+ to collect accurate denominator data in a systematic way. In order to calculate uptake, denominator totals were estimated based on applying a correction factor to the total numbers of women recorded as being pregnant (at any stage of pregnancy), as provided by General Practice through Audit+. These figures represent a cumulative measure of coverage throughout the campaign, rather than being a snapshot in women who are currently in their third trimester of pregnancy. Numbers of women newly recorded as being pregnant were used as a proxy for numbers of women becoming newly eligible to receive pertussis immunisation, as a result the estimated denominator does not compensate for women who do not reach week 28 of their pregnancy, and may therefore be larger than the number of women eligible for immunisation. The analysis also assumed that all women would have had equal opportunity to be immunised. 2 (2014). Update 21 on Progress in Influenza Immunisation Campaign , aee80257c f34/$file/weekly_flu_imm_summary.pdf Date: March 2014 Version: 2 Page: 4 of 19

5 Point of delivery surveillance survey Methodology The cohort included in the survey was defined as all pregnant women delivering in Wales in the period 20 th 24 th January All maternity services agreed to collect the data using the questionnaire at appendix 1 for five days. It was recognised that it may not be possible for data to be collected for all five days and units were advised that shorter periods were acceptable for estimating uptake. The Heads of Midwifery in all seven health boards agreed to participate 13 main maternity units in Wales were included in the survey Information from newly delivered women about pertussis vaccination, weeks gestation when vaccinated and weeks gestation at delivery was collected by midwifery staff Information about offer and receipt of influenza vaccination was also collected Data collected for five days from 20 th 24 th January (one unit in one HB collected data for one day ) An estimate for the number of births in a five day period in the health board was calculated using live and still births data for 2012 from Welsh Government statistics (Appendix 2). There are differences in the estimates of births for a five day period and some health board births data due to a variety of reasons: Only the main maternity units for each health board participated, some health boards have small community maternity units that did not participate in the survey One maternity unit in one health board returned data for one day only. This was the largest maternity unit in that health board. The estimate of live births during a five day period calculated from the 2012 statistics is based on an average five day period and does not take in to account seasonal fluctuations in birth rate. Powys health board is a rural area with no district general hospital its annual birth rate, delivered in the health board area for 2012 was 132. Results In order to estimate the completeness of the survey the numbers participating were compared with estimated numbers of deliveries in a five day period based on actual delivery data for a previous year. Table 1 shows estimated numbers of the women expected to deliver during the Date: March 2014 Version: 2 Page: 5 of 19

6 period who were included in this survey, based on the Welsh Government 2012 birth statistics (Appendix 2). A sample of 453 was estimated, data was collected from 430 women (94.9%). This suggests the survey included most women delivering in the survey period. Table 1 The number of women participating in the survey compared with the estimated number who delivered in the unit during the five day period. Health Board Estimated number of births in 5 day period* ABMU Aneurin Bevan** Betsi Cadwaladr Cardiff & Vale Cwm Taf Hywel Dda Powys Teaching 2 2 Total Number of women with uptake data *Source: WG Stats Wales live and still births data for 2012 ** Data returned from 1 unit for 1 day Pertussis Vaccination Coverage of pertussis vaccination in women included in this survey was 69.3% for Wales, and ranged by health board from 51.5% to 100% (Table 2, Figure 1). Table 2 Estimate of uptake of pertussis vaccine in Wales Received pertussis vaccination while pregnant Number of women Percentage Yes % No % Not known/missing % Total % Date: March 2014 Version: 2 Page: 6 of 19

7 Uptake Uptake Figure 1 The percentage uptake of pertussis vaccination in pregnant women by Health Board (n=430) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Percentage uptake of pertussis vaccination in pregnant women by Health Board (n=430) 51.5% ABMU 67.5% Aneurin Bevan 82.8% Betsi Cadwaladr 76.5% Cardiff & Vale Health Board 90.9% 54.5% 100.0% Cwm Taf Hywel Dda Powys Teaching Coverage of pertussis vaccination by age group was highest (77.1%) in women aged years and lowest in (44.4%) in women aged 40 years and older (Figure 2). Figure 2 Percentage uptake of pertussis vaccination in pregnant women by age group (n=421) 100% Percentage uptake of pertussis vaccination in pregnant women by age group (n=421) 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 76.0% 77.1% 62.2% 44.4% Under 20y (n=25) 20-29y (n=217) 30-39y (n=170) 40y+ (n=9) Age group Date: March 2014 Version: 2 Page: 7 of 19

8 Number of women The proportion of women vaccinated in the recommended period of gestation weeks was 76.7%, weeks was 15.3%, and overall weeks was 92.0% (Figure 3). Gestational week at delivery for women who had received pertussis vaccination ranged from 28 weeks to 43 weeks (Figure 4), and 95.3% of women delivered between 36 and 42 weeks. The mean interval between pertussis vaccination and delivery was 10 weeks (Figure 5), and ranged from 0 weeks to 21 weeks. Figure 3 Number of weeks gestation when vaccinated 120 Number of weeks gestation when vaccinated (n=275) Number of weeks gestation Date: March 2014 Version: 2 Page: 8 of 19

9 Number of women Number of women Figure 4 Number of weeks gestation at delivery for those who received pertussis vaccination Number of weeks gestation delivered for those who received pertussis vaccine (n=254) Weeks gestation at delivery Figure 5 Number of weeks interval between pertussis vaccination and delivery Number of weeks between pertussis vaccine and delivery (n=244) Weeks between vaccination and delivery Date: March 2014 Version: 2 Page: 9 of 19

10 Women were also asked if they were offered pertussis vaccine during their pregnancy. Table 3 shows that more than 4 in 5 women (85.3%) reported they were offered the vaccine during pregnancy, about 1 in 8 women (12.3%) did not recall being offered the vaccine. Table 3 Number of women who report being offered pertussis vaccine during pregnancy Offered pertussis vaccination while pregnant Influenza vaccine Number of women Percentage Yes % No % Not known/missing % Total % Women were asked if they received influenza vaccine during pregnancy, Table 4 shows that 70.5% of pregnant women received influenza vaccine. Table 4 Number of women receiving influenza vaccine during pregnancy Received influenza vaccination while pregnant Number of women Percentage Yes % No % Not known/missing % Total % Table 5 shows that 9 in 10 pregnant women (90.7%) report they were offered influenza vaccine. Only 1 in 15 pregnant women (3.0%) reported they were not offered an influenza vaccine. Table 5 Number of women who report being offered influenza vaccine during pregnancy Offered influenza vaccination while pregnant Number of women Percentage Yes % No % Not known/missing % Total % Date: March 2014 Version: 2 Page: 10 of 19

11 Uptake Uptake Figure 6 The percentage uptake of influenza vaccination in pregnant women by Health Board (n=430) 100% Percentage uptake of influenza vaccination in pregnant women by Health Board (n=430) 100.0% 80% 66.7% 65.0% 79.6% 79.0% 68.2% 60% 40% 47.3% 20% 0% ABMU Aneurin Bevan Betsi Cadwaladr Cardiff & Vale Health Board Cwm Taf Hywel Dda Powys Teaching Uptake of influenza vaccination in pregnant women was 70.5% for Wales, it ranged by Health Board from 47.3% to 100 % (Figure 6). Figure 7 Percentage uptake of influenza vaccination in pregnant women by age group (n=421) 100% Percentage uptake of influenza vaccination in pregnant women by age group (n=421) 80% 68.0% 67.7% 73.5% 66.7% 60% 40% 20% 0% Under 20y (n=25) 20-29y (n=217) 30-39y (n=170) 40y+ (n=9) Age group Date: March 2014 Version: 2 Page: 11 of 19

12 Uptake of influenza vaccination by age group was highest (73.5%) in women aged years and lowest in (66.7%) in women aged 40 years and older (Figure 7). Pertussis and Influenza vaccine Overall 61.9% (266/430) of women received both vaccines and 89.3% (266/298) of women who received pertussis vaccine also received the influenza vaccine (Table 6). Table 6 Number of women receiving both the pertussis and flu vaccine while pregnant Received influenza vaccine while pregnant Received pertussis vaccine when pregnant Not known/ No Yes Total missing Not known/ missing No Yes Total Trends in uptake Table 7 Estimates of pertussis uptake in Health Boards in Wales in 2012/13 and 2013/14 seasons Health Board % received pertussis vaccination 2013 % received pertussis vaccination 2014 ABMU 43.8% 51.5% Aneurin Bevan 59.2% 67.5% Betsi Cadwaladr 72.5% 82.8% Cardiff & Vale 66.1% 76.5% Cwm Taf 70.8% 90.9% Hywel Dda 67.7% 54.5% Powys Teaching 100.0% 100.0% All Wales 63.4% 69.3% Date: March 2014 Version: 2 Page: 12 of 19

13 Uptake 43.8% 51.5% 59.2% 67.5% 54.5% 72.5% 82.8% 66.1% 76.5% 70.8% 67.7% 63.4% 69.3% 90.9% 100.0% 100.0% Figure 8 Comparison of the percentage uptake of pertussis vaccination in pregnant women by Health Board between 2012/13 and 2013/14 seasons Percentage uptake of pertussis vaccination in pregnant women by Health Board 2013 and % 90% % 70% 60% 50% 40% 30% 20% 10% 0% ABMU Aneurin Bevan Betsi Cadwaladr Cardiff & Vale Health Board Cwm Taf Hywel Dda Powys Teaching All Wales Coverage of pertussis vaccination in women included in the point of delivery surveys increased by 5.9% in Wales between 2013 and Five out of the seven health boards reported higher uptakes in (Table 7, Figure 8). Table 8 Estimates of influenza uptake in Health Boards in Wales in 2012/13 and 2013/14 seasons Health Board % received influenza vaccination 2013 % received influenza vaccination 2014 ABMU 36.3% 66.7% Aneurin Bevan 71.4% 65.0% Betsi Cadwaladr 67.5% 79.6% Cardiff & Vale 68.6% 79.0% Cwm Taf 62.5% 68.2% Hywel Dda 63.1% 47.3% Powys Teaching 100.0% 100.0% All Wales 61.6% 70.5% Date: March 2014 Version: 2 Page: 13 of 19

14 Uptake 36.3% 47.3% 66.7% 71.4% 65.0% 67.5% 79.6% 68.6% 79.0% 62.5% 68.2% 63.1% 61.6% 70.5% 100.0% 100.0% Figure 9 Comparison of the percentage uptake of influenza vaccination in pregnant women by Health Board between 2012/13 and 2013/14 seasons Percentage uptake of influenza vaccination in pregnant women by Health Board 2013 and % 90% % 70% 60% 50% 40% 30% 20% 10% 0% ABMU Aneurin Bevan Betsi Cadwaladr Cardiff & Vale Health Board Cwm Taf Hywel Dda Powys Teaching All Wales Coverage of influenza vaccination in women included in the point of delivery surveys increased by 8.9% in Wales between 2012/13 and 2013/14. Four out of the seven health boards reported higher uptakes in (Table 8, Figure 9). Conclusions Coverage of pertussis and influenza immunisations as recalled by women delivering between 20 th - 24 th January 2014 in Wales was: 69.3% of pregnant women received pertussis vaccination 70.5% of pregnant women received influenza vaccination 61.9% of pregnant women received both pertussis and influenza vaccination Also more than 4 in 5 women recalled being offered the vaccines during pregnancy Compared with uptakes last year there has been a 5.9 % increase from 63.4% to 69.3% in pertussis uptake and an 8.9% increase from 61.6% to 70.5% in influenza uptake reported by women in the survey. These figures Date: March 2014 Version: 2 Page: 14 of 19

15 provide robust estimates of coverage of pertussis and influenza vaccination in pregnant women at the time of birth. Audit+ data on uptake in women who have been recorded as pregnant at some point during the flu vaccination season is useful to compare uptake by place and over time. However the data has well known limitations and is not an indicator or uptake in women pregnant at any one point in time. It is expected that data collected through Audit+ will produce lower estimates of coverage than the point of delivery audit, as different populations have been sampled in each survey. Data collected from General Practices on uptake of immunisation during pregnancy will include women whose pregnancies do not end in delivery of a child; as a result the denominator will be inflated compared to the population being sampled in the point of delivery audit and uptake will appear lower. Although the 75% uptake target for influenza set by Welsh Government has not been reached the results from this survey are very encouraging. They highlight the confidence that pregnant women have in accepting both pertussis and influenza vaccines and the effectiveness of primary care and midwifery services to deliver the programmes. No pertussis related infant deaths were reported in England and Wales between July and September 2013 compared to 5 deaths in the same quarter in 2012 (PHE 2013). It is important to be aware that high levels of pertussis persist in older age groups (PHE 2014). Women should continue to be encouraged to be immunised against pertussis during pregnancy in order to protect their babies from birth. Acknowledgement We are very grateful for the support of the Heads of Midwifery and the midwives who participated in this survey. Date: March 2014 Version: 2 Page: 15 of 19

16 References Australian Government (2013): Pertussis (Whooping Cough), unise-pertussis [Accessed 30 th May 2013] Fisman DN. et al (2011) Pertussis resurgence in Toronto, Canada: a population-based study including test-incidence feedback modelling, BMC public health 2011; Health Protection Agency (2012) Laboratory confirmed cases of Pertussis infection, England and Wales, by region and age group, 2008 to 2012 Q1-2 (confirmed by culture, PCR and/or serology). Available at; [Accessed 30 th May 2013] Joint Committee on Vaccination Immunisation (JCVI) (2012) Meeting on pertussis immunisation. August [Accessed 30 th May 2013] Kmietowicz Z. (2012) Pertussis cases rise 10-fold among older children and adults in England and Wales. BMJ 345:e Public Health England (2014) Health Protection Report Vol 8 No 6. Published 14 Feb [Accessed 25 th Feb 2014] (2013). Number of laboratory confirmed pertussis cases, notifications and rates per 100,000 in Wales: Available at; [Accessed 18 Feb 2014] (2014). Update on Progress in Influenza Immunisation Campaign Available at; 9ec baee80257c f34/$FILE/Weekly_Flu_Imm_Summary. pdf [Accessed 25 Feb 2014} Welsh Government (2013). Extension to the Pertussis vaccination Programme of Pregnant Women. CMO (2013) th July sis Date: March 2014 Version: 2 Page: 16 of 19

17 Winter K, Harrison K, Zipprich J et al (2012) California Pertussis Epidemic The Journal of Paediatrics. Date: March 2014 Version: 2 Page: 17 of 19

18 Appendices Appendix 1. Point of delivery data collection form Date: March 2014 Version:v2 Page: 18 of 19

19 Appendix 2 Maternity Units in Wales s approx births/year, Source: WG Stats Wales live and still births data for Health/BirthsLiveAndStill-by-WelshBirthUnit-LocalHealthBoard-Year Health Board Cardiff and Vale Aneurin Bevan Abertawe Bro Morgannwg* Betsi Cadwaladr 2012 Approx Annual births/ deliveries Estimate weekly births/ deliveries Estimate of births/ Deliveries in 5 days UHW 6033 Main Maternity Units Royal Gwent 3501 Neville Hall Hospital Singleton 3387 Princess of Wales Ysbyty Glan Clwyd 2376 Wrexham Maelor 2664 Ysbyty Gwynedd 2210 Smaller midwifery units Ystrad Fawr 372 Ysbyty Aneurin Bevan 23 Neath Port Talbot 387 Bryn Beryl 3 Dolgellau 5 Tywyn & District 2 Powys Brecon, Llandrindod Wells, Knighton, Llanidloes, Newtown, Welshpool. Cwm Taf Prince Charles 1661 Royal Glamorgan 2269 Hywel Dda Withybush 1318 West Wales 1667 Aberdare General 114 Bronglais 552 Total *Abertawe Bro Morgannwg includes two births with unknown unit Date: March 2014 Version: 2 Page: 19 of 19