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This publication is available at https://www.gov.uk/government/publications/pertussis-immunisation-in-pregnancy-vaccine-coverage-estimates-in-england-october-2013-to-march-2014/pertussis-vaccination-programme-for-pregnant-women-vaccine-coverage-estimates-in-england-april-to-august-2014
1. Background to the pertussis vaccination in pregnancy programme
In the UK the introduction of routine national immunisation against pertussis in 1957 resulted in a marked reduction in pertussis notifications and deaths . Despite a sustained period of high vaccine coverage since the early 1990s, pertussis has continued to display 3-4 yearly peaks in activity. In the five years prior to 2012, on average, there were nearly 800 confirmed cases of whooping cough, 270 babies admitted to hospital and four deaths in babies each year [HPA unpublished reconciled data]. The highest disease incidence occurs in infants under three months of age who are too young to have completed the primary vaccine course and have the greatest risk of complications and death. In 2012, pertussis activity increased beyond levels reported in the previous 20 years and extended into all age groups, including infants less than three months of age. This young infant group is considered a key indicator of pertussis activity  and the primary aim of the pertussis vaccination programme is to minimise disease, hospitalisation and death in young infants.
A national outbreak (level 3 incident) was declared in April 2012 by the then Health Protection Agency to coordinate the response to increased pertussis activity . In response to this on-going outbreak, the Department of Health announced that pertussis immunisation would be offered to pregnant women from 1 October 2012 to protect infants from birth whilst disease levels remain high . This programme aims to passively protect infants from birth, through intrauterine transfer of maternal antibodies, until they can be actively protected by the routine infant programme with the first dose of pertussis vaccine scheduled at eight weeks of age.
Pertussis activity in England persists at raised levels compared to the years preceding the outbreak in 2012 . The greatest reduction in disease since the peak in 2012 has been in infants under six months of age who are targeted by the maternal pertussis vaccination programme. Disease incidence has, as expected, continued to be highest in this age group but case reports are now in line with those seen before the 2012 peak. There have been six deaths reported in young babies (under 10 weeks) diagnosed with pertussis to the end of August this year: in total nine deaths have been reported in young babies with confirmed pertussis who were born after the introduction of the pregnancy programme on 1 October 2012. Eight of these nine babies were born to mothers who had not been vaccinated against pertussis, all of the nine babies were too young to be fully protected by vaccination themselves and none had received their first dose of pertussis-containing vaccine .
A UK study examining the safety of pertussis vaccination in pregnancy found no evidence of an increased risk of any of an extensive predefined list of adverse events related to pregnancy for women given pertussis vaccination in the third trimester . Effectiveness of maternal pertussis vaccination in preventing disease in infants younger than three months of age in England, has been calculated at 91% (95% confidence interval 84 to 95%) . This June the Joint Committee on Vaccination and Immunisation (JCVI) considered available data relating to the coverage, effectiveness and safety of the programme, its impact on disease and current epidemiology and advised that the programme should continue for a further five years . This includes the continuation of all surveillance activities introduced to monitor the programme.
2. Vaccine coverage collection
In England, monthly data on the uptake of pertussis immunisation in pregnancy are collected through the ImmForm website and are monitored, validated and analysed by PHE. This data collection is vital to monitor the uptake of the programme, to identify areas of low coverage and inform public health actions.
Since May 2014, ie for data from April 2014 onwards, data have been automatically uploaded from participating GP practices to the ImmForm website and analysed by Area Team. This method has the potential to collate data from up to 90% of GP practices in England, and replaces the manual system that was previously in use .
The automated system uses the more accurate recorded date of delivery as opposed to the estimated date of delivery (EDD) that was used in the manual system. Hence the monthly denominator for automated data is the number of women who delivered in the survey month at more than 28 weeks gestational age; the monthly numerator is the number of pregnant women who delivered after 28 weeks gestational age in the survey month that received a dose of pertussis-containing vaccine in the preceding fourteen weeks. During the summer of 2014 Boostrix-IPV® replaced Repevax® as the pertussis-containing vaccine used for pregnant women .
Unlike the manual system, in addition to the numerator and denominator, the automated system records the number and percentage of GP practices responding each month. For accurate denominators to be extracted from GP IT systems by the automated survey it is important that the medical records of all women who have given birth have the following fields completed: * the date of delivery * date of receipt of a pertussis-containing vaccine at or after week 28 of pregnancy, regardless of the setting where the vaccine was administered * where relevant, any record of a premature delivery occurring at less than 28 weeks gestational age.
Continued support in the delivery of this important programme is being sought from service providers (GP practices and maternity units), Screening and Immunisation Teams and Health Protection Teams. Screening and Immunisation Teams should continue to update service providers on the current epidemiology of the disease, the effectiveness of the vaccination programme and the need to continue to improve the current coverage levels. Further information on the pertussis vaccination programme for pregnant women is available here: https://www.gov.uk/government/collections/pertussis-guidance-data-and-analysis.
This report updates the previous summary of the pertussis vaccination programme for pregnant women for the six months ending 31 March 2014 , when data was still collected using the manual reporting system.
The figure shows a decrease in the overall monthly estimates of pertussis vaccine coverage in pregnant women since the introduction of the automated system (in the six months prior to April 2014 coverage had averaged at around 60%). However, despite an initial drop in coverage, between April and August 2014 coverage across England then increased from 52.7% to 55.6%, coinciding with a steady increase in the proportion of GP practices participating each month (from 77.6% to 90.7%).
The table shows vaccine coverage by Area Team for the period April to August 2014 (data for previous months by Area Team are available here: https://www.gov.uk/government/collections/vaccine-uptake#pertussis-vaccine-uptake-in-pregnant-women. During the first month of automated reporting (data for April 2014) six of the 25 Area Teams recorded vaccine coverage below 50%. However, by August 2014 all Area Teams except two (Birmingham and the Black Country, and London) were reporting >50% coverage, with nine Area Teams reporting ≥60% coverage. This compares with 14 Area Teams achieving ≥60% in March 2014.
One GP IT supplier was unable to provide data for many of their practices in April. As a result two Area Teams with a high proportion of their GPs served by this supplier had less than half of their GP practices reporting in the first month of automated reporting. From May to August 2014 all Area Teams had at least 70% of GP practices reporting. By August 2014 all Area Teams except one (Greater Manchester) had >80% of GP practices reporting, with five Area Teams reporting data from >95% of GP practices.
There did not appear to be a clear relationship between the percentage of GP practices participating and the number of women included in each survey at the Area Team level. This may be due to variations in the sizes of GP practices reporting each month or there may be differences between the different GP IT suppliers in the completeness of recording the delivery data on the mother’s medical record.
Based on a total of 657,177 maternities (a maternity is defined as a pregnancy resulting in the birth of one or more children, including stillbirths) in England each year (2013), the number of pregnant women with a delivery in any one month is on average 54,765 , though there is variation in the number of maternities by month across the year . The total number of women reported in each survey continued to vary considerably, both by month of report and by Area Team, as well as within Area Teams each month. The highest number of women reported in the denominator in the five month period was for July 2014 when 39,438 women who delivered in the survey month at more than 28 weeks gestational age were included in the collection, approximately 72% of the expected England total; the smallest number of women reported was for April, with 25,498 women, representing only 47% of the expected maternities (table).
The national coverage estimates reported between April and August 2014 average at around 54%, a decline on the 60% reported in the previous six months , but coverage appears to be gradually increasing.
Data should be interpreted with caution for several reasons. The methodology used for collecting coverage data changed from a manual to an automated collection in April 2014, and the definition of the denominator changed from the estimated delivery date to the recorded delivery date. Coverage may be over-estimated if women who have received the vaccine are more likely to have their delivery date recorded.
In addition, this is a sentinel system and at best, will represent data from around 90% of all GP practices in England. Data is not uploaded for all GP practices each month and there may be variation between the reporting practices in the completeness of the recording of delivery dates in the mother’s medical records, hence, as demonstrated by comparison with national data on births and deliveries, these returns are incomplete… Furthermore, women not registered with a GP (and therefore less likely to be having regular contact with the health service prior to delivery) will not be captured by this reporting system.
However, despite these factors contributing to potential over-estimation of coverage, comparison with other data sources examined to estimate the vaccine uptake of this programme suggests that this methodology may be underestimating coverage. The Clinical Practice Research Datalink, a primary care dataset containing anonymised information for patients registered at 520 English general practices representative of the population of England in terms of geographical distribution found that estimated coverage peaked at 78% with a low of 60% for women who had a live birth between 1st October 2012 and 3rd September 2013 . Over the same period national coverage peaked at 60% and fell to a low of 50% .
5.1 Monthly pertussis vaccine coverage (%) for pregnant women by Area Team: England, April to August 2014
|Area Team||April 2014||May 2014||June 2014||July 2014||August 2014|
|Cheshire, Warrington and Wirral (Q44)||61.4||59.5||60.0||62.6||61.7|
|Durham, Darlington and Tees (Q45)||60.5||57.2||59.4||57.0||57.7|
|Greater Manchester (Q46)||47.7||50.8||50.8||52.1||52.8|
|Cumbria, Northumberland, Tyne and Wear (Q49)||52.9||58.6||57.5||57.9||60.0|
|North Yorkshire and Humber (Q50)||60.9||60.9||66.3||60.5||61.8|
|South Yorkshire and Bassetlaw (Q51)||59.8||62.1||64.2||59.5||64.0|
|West Yorkshire (Q52)||65.4||61.8||65.2||59.6||63.2|
|Arden, Herefordshire and Worcestershire (Q53)||49.3||53.2||51.3||51.3||52.3|
|Birmingham and the Black Country (Q54)||48.9||49.5||51.2||48.4||49.2|
|Derbyshire and Nottinghamshire (Q55)||66.7||65.8||65.9||62.7||63.9|
|East Anglia (Q56)||60.6||60.5||57.2||55.8||55.5|
|Hertfordshire and the South Midlands (Q58)||60.7||59.7||61.0||54.9||56.9|
|Leicestershire and Lincolnshire (Q59)||60.4||58.8||61.5||53.0||57.6|
|Shropshire and Staffordshire (Q60)||58.7||54.4||59.2||55.9||56.2|
|Bath, Gloucestershire, Swindon and Wiltshire (Q64)||64.7||63.6||62.1||62.3||63.0|
|Bristol, North Somerset, Somerset and South Gloucestershire (Q65)||52.5||55.5||56.1||54.5||53.9|
|Devon, Cornwall and Isles of Scilly (Q66)||50.8||49.7||50.6||48.7||52.9|
|Kent and Medway (Q67)||49.1||51.2||47.9||54.0||54.6|
|Surrey and Sussex (Q68)||55.7||57.4||53.6||54.7||56.2|
|Thames Valley (Q69)||53.2||56.4||56.1||54.3||60.2|
|Monthly reported denominator||25,498||30,958||30,087||39,438||35,587|
- Amirthalingam G, Gupta S, Campbell H (2013). Pertussis immunisation and control in England and Wales, 1957 to 2012: a historical review. Euro. Surveill. 18(38), http://eurosurveillance.org/images/dynamic/EE/V18N38/art20587.pdf
- Campbell H, Amirthalingam G, Andrews N, Fry NK, George RC, Harrison TG, et al (2012). Accelerating control of pertussis in England and Wales. Emerging Infectious Diseases 18(1): 38-47.
- A level 3 incident is the third of five levels of alert under the PHE’s Incident Reporting and Information System (IERP) according to which public health threats are classified and information flow to the relevant outbreak control team is coordinated. A level 3 incident is defined as one where the public health impact is significant across regional boundaries or nationally. An IERP level 3 incident was declared in April 2012 in response to the ongoing increased pertussis activity (HPR 6(15))
- “Pregnant women to be offered whooping cough vaccination”, 28 September 2012. Department of Health website, http://www.dh.gov.uk/health/2012/09/whooping-cough/
- PHE. “Laboratory confirmed pertussis in England: data to end-August 2014”, HPR 8(38): news, 3 October 2014, https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/361588/hpr3814_prtsss.pdf
- Donegan K, King B, Bryan P. Safety of pertussis vaccination in pregnant women in UK: observational study. BMJ 2014, http://www.bmj.com/content/349/bmj.g4219 .
- Amirthalingam G, Andrews N, Campbell H, Ribeiro S, Kara E, Donegan K, Fry NK, Miller E, Ramsay M. Effectiveness of maternal pertussis vaccination in England: an observational study. Lancet 2014. Lancet 2014 http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(14)60686-3/abstract
- Joint Committee on Vaccination and Immunisation minutes, https://www.gov.uk/government/groups/joint-committee-on-vaccination-and-immunisation#minutes.
- PHE. Pertussis Vaccination Programme for Pregnant Women: vaccine coverage estimates in England, October 2013 to March 2014, HPR 8(17): immunisation, 2 May 2014, https://www.gov.uk/government/publications/pertussis-immunisation-in-pregnancy-vaccine-coverage-estimates-in-england-october-2013-to-march-2014
- Replacement whooping cough vaccine. Vaccine Update (issue 213), March 2014
- Office for National Statistics. Births by usual area of residence of mother, UK, 2013
- Office for National Statistics. Characteristics of Birth 2, England and Wales, 2012
- PHE. Pertussis vaccine uptake in pregnant women October 2012 to March 2014: monthly data by area team (England)