Laboratory confirmed cases of pertussis in England: annual report for 2022
Updated 23 May 2024
Applies to England
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In England, there were 68 new laboratory confirmed cases of pertussis (culture, PCR, serology or oral fluid) reported to the UK Health Security Agency (UKHSA) pertussis enhanced surveillance programme in 2022. The 68 confirmed cases in England were 39% lower than the 49 reported in 2021 (figure 1).
Total number of samples submitted to UKHSA for testing were 32% lower in 2022 (13,128) compared to 2021 (19,254) with a positivity rate of 0.6% (75 of 13,041) in 2022 and 0.3% (62/19,176) in 2021.
Figure 1. Total number of laboratory confirmed pertussis cases per quarter in England, 2011 to 2022
The coronavirus (COVID-19) pandemic and the implementation of social distancing measures and lockdown across the UK from 23 March 2020 had a significant impact on the spread and detection of other infections including pertussis. From July 2021, COVID-19 containment measures were withdrawn in England. Vaccination against pertussis and other infectious diseases continues to be important as increasing levels of these diseases are expected following the easing of control measures.
Pertussis is a cyclical disease, with increases occurring every 3 to 4 years, with pertussis activity usually peaking each year in quarter 3 (July to September). In 2022, the highest proportion of cases was observed in the fourth quarter (October to December), when 27 cases (40%) were reported followed by 19 cases (28%) between July and September. Thirteen cases were reported in April to June and 9 cases in January to March (table 1).
The national incidence for all age groups, based on laboratory confirmed cases of pertussis in England and 2022 population estimates (1) was 0.1 per 100,000 in 2022 compared to 1.8 per 100,000 in 2020 and 6.5 per 100,000 in 2019; it reached 17.5 per 100,000 in 2012 (epidemic peak year). Prior to the major peak in 2012, incidence ranged between 0.4 per 100,000 and 2.0 per 100,000 (figure 2).
Laboratory confirmed pertussis cases in infants aged under 1 year remained low with 5 cases reported in 2022 and 2 cases in 2021 compared to 50 cases in 2020. This compares with 508 confirmed cases reported in the outbreak year in 2012.
There has been a decline in pertussis incidence in infants under 3 months of age since the introduction of the maternal vaccination programme, from 234 per 100,000 in 2012 to 93 per 100,000 in 2016, 20 per 100,000 in 2020 and 1.3 per 100,000 in 2022 (figure 2). Two infants aged under 3 months were confirmed in 2022 and one case in 2021 compared to 30 cases confirmed in 2020. The number of confirmed cases in infants under 3 months and overall for infants under 1 year of age in 2022 were the second lowest reported since the introduction of enhanced surveillance in 1994, the lowest being reported in 2021.
Cases in infants aged 3 to 5 months has also remained low since the 2012 epidemic peak when there were 74 cases (43 per 100,000). There were 3 cases (2 per 100,000) in this age group in 2022 compared to 1 case (0.7 per 100,000) in 2021 and 15 (10 per 100,000) in 2020.
In the 2016 cyclical peak, confirmed cases aged between 6 and 11 months were higher (34 cases, 10 per 100,000) than in any year since the introduction of enhanced surveillance. In 2019, incidence in this age group was 7 per 100,000 (21 cases) – in 2020 it was 2 per 100,000 (5 cases). There were no reported cases in infants aged between 6 and 11 months in 2022 and in 2021. These low numbers are consistent with protection from primary vaccination offered at 2, 3 and 4 months of age in conjunction with measures introduced to control the SARS-CoV-2 pandemic.
The number of children aged 1 to 4 years confirmed with pertussis increased from 3 cases in 2021 to 10 cases in 2022. Laboratory confirmed pertussis cases in individuals aged 15 years and older were 21% higher in 2022 (47 cases) than in 2021 (39 cases). In children aged 5 to 14 years, numbers of confirmed cases in 2022 were similar to 2021 (6 and 5 respectively). Ascertainment in those aged 5 to less than 17 years has improved with availability of oral fluid testing since 2013. From 1 May 2018, the availability of oral fluid testing was extended to all children aged from 2 up to and including 16-year-olds, which may underpin earlier increases observed in the 1 to 4 year age group. In 2022 oral fluid alone accounted for 63% (10 of 16) of cases in children aged between 1 and 14 years.
A third (69%; 47 of 68 cases) (table 2) of laboratory confirmed cases in England in 2021 occurred in individuals aged 15 years and older – compared to 80% (39 of 49 cases) in 2021. Total numbers in this age group in 2022 were 21% higher than in 2021.
Deaths
In England, 14 deaths were reported in infants with confirmed pertussis in the 2012 epidemic peak year. Following the introduction of pertussis vaccination in pregnancy there have been 20 further deaths in babies with confirmed pertussis. There were no reported deaths in infants with confirmed pertussis between 2020 and 2022.
All the deaths in 2012, and those that occurred between the introduction of the maternal programme and end-December 2022, were too young to be fully protected by infant vaccination. Only 2 of these 20 infants born after the introduction of the maternal programme had a mother who had been vaccinated during pregnancy. In both cases the vaccination was too close to delivery to confer optimal passive protection in the infant. Estimated vaccine effectiveness against death in infants with pertussis whose mothers had been vaccinated was very high at 97% (2) based on pertussis cases from 2013 to 2019.
Childhood vaccination uptake
The national vaccination schedule recommends pertussis vaccination at 8, 12 and 16 weeks of age and a pre-school booster at 3 years and 4 months.
Vaccine coverage estimates for 2022, evaluated between October and December for DTaP/IPV/Hib/HepB immunisation across England, was 91.9% for 3 doses at 12 months of age and 84.0% for the booster dose by 5 years of age (3). Coverage estimates for DTaP/IPV/Hib at 12 months of age were slightly lower than the coverage estimates for October to December 2021 when the proportion of children vaccinated at 12 months was 92.0% and coverage estimates for the booster dose were lower than the 85.2% reported (4).
The introduction of social distancing in response to the COVID-19 pandemic from late March 2020, when some of this cohort would have been scheduled for vaccination, may have contributed to the modest decrease seen in the booster dose coverage.
Maternal vaccination programme
The maternal pertussis immunisation programme (5, 6) introduced in response to the 2012 outbreak became permanent from June 2019 (7) based on evidence of disease impact, high effectiveness and safety (8, 9, 10, 11). The recommended gestational age for vaccination is between 20 and 32 weeks, ideally after the 20-week scan, but the vaccine can be given as early as 16 weeks (7) for pragmatic reasons to ensure vaccination.
UKHSA reported that the proportion of mothers due to give birth in 2022 who had been immunised with a pertussis containing vaccine in pregnancy in England ranged from a monthly average of 59.5% (June) to 64.3% (January) compared to 2021 when monthly averages ranged from 63.1% (May) to 67.8% (January) (12).
Surveillance data in young infants following the introduction of the pertussis immunisation in pregnancy programme demonstrated that a low incidence had been maintained in this age group, with expected seasonal increases. COVID-19 control measures appear to have had an additional impact on these observed effects. With the withdrawal of COVID-19 containment measures and increased social mixing it is expected that the number of cases will increase and therefore it is even more important that women are offered pertussis vaccination in pregnancy (ideally between 20 and 32 weeks), to optimise protection for their babies from birth, and for infants to complete the vaccination schedule on time.
Note: UKHSA began publishing monthly epidemiological data for pertussis in England from March 2024.
Supplementary data tables from 1994 to 2022 are available.
Figure 2. Incidence of laboratory confirmed pertussis cases by age group in England: 1998 to 2022
Table 1. Laboratory confirmed cases of pertussis by quarter and test method* in England: 2022
| Quarter | Culture | PCR | Serology | Oral fluid only | Total |
|---|---|---|---|---|---|
| January - March | 0 | 0 | 7 | 2 | 9 |
| April - June | 0 | 3 | 7 | 3 | 13 |
| July - September | 0 | 3 | 14 | 2 | 19 |
| October - December | 1 | 6 | 17 | 3 | 27 |
| Total | 1 | 12 | 45 | 10 | 68 |
*Culture-confirmed cases may additionally have tested positive by any other method; PCR-confirmed cases may have additionally tested positive by serology or OF; and serology-confirmed cases may also have been confirmed by OF. Cases are only represented once in the table. Submission of all presumptive B. pertussis isolates is encouraged for confirmation of identity and to allow further characterisation for epidemiological purposes.
Table 2. Age distribution of laboratory confirmed cases of pertussis by test method* in England: 2022
| Age group | Culture | PCR | Serology | Oral fluid only | Total |
|---|---|---|---|---|---|
| Less than 3 months | 0 | 2 | 0 | 0 | 2 |
| 3 to 5 months | 0 | 3 | 0 | 0 | 3 |
| 6 to 11 months | 0 | 0 | 0 | 0 | 0 |
| 1 to 4 years | 0 | 4 | 0 | 6 | 10 |
| 5 to 9 years | 0 | 1 | 1 | 1 | 3 |
| 10 to 14 years | 0 | 0 | 0 | 3 | 3 |
| 15 years and over | 1 | 2 | 44 | 0 | 47 |
| Total | 1 | 12 | 45 | 10 | 68 |
*Culture-confirmed cases may additionally have tested positive by any other method; PCR-confirmed cases may have additionally tested positive by serology or OF; and serology-confirmed cases may also have been confirmed by OF. Cases are only represented once in the table. Submission of all presumptive B. pertussis isolates is encouraged for confirmation of identity and to allow further characterisation for epidemiological purposes.
References
1. Office for National Statistics, 2020 population estimates
2. Amirthalingam G, and others (2023). Optimization of timing of maternal pertussis immunization from 6 years of post-implementation surveillance data in England
3. Quarterly vaccination coverage statistics for children aged up to 5 years in the UK (COVER programme): October to December 2022. Health Protection Report volume 17 number 3, 28 March 2023
4. Quarterly vaccination coverage statistics for children aged up to 5 years in the UK (COVER programme): October to December 2021. Health Protection Report volume 16 number 4, 29 March 2022
5. Confirmed pertussis in England and Wales continues to increase (2012). Health Protection Report volume 6 number 15, 13 April 2012
6. Department of Health (2012) Pregnant women to be offered whooping cough vaccine (website news story, 28 September)
7. Joint Committee on Vaccination and Immunisation (2014). Minute of the meeting on 4 June 2014
8. Amirthalingam G and others (2014). Effectiveness of maternal pertussis vaccination in England: an observational study. The Lancet
9. Dabrera G, and others (2014). A case-control study to estimate the effectiveness of maternal pertussis vaccination in protecting newborn infants in England and Wales, 2012 to 2013. Clinical Infectious Diseases
10. Donegan K, and others (2016). Safety of pertussis vaccination in pregnant women in UK: observational study. British Medical Journal
11. Amirthalingam G and others (2016) Sustained effectiveness of the maternal pertussis immunization program in England 3 years following introduction, Clinical Infectious Diseases
12. Pertussis vaccination programme for pregnant women update: vaccine coverage in England, October to December 2022. Health Protection Report volume 17 number 5, 4 April 2023
13. Pertussis vaccination programme for pregnant women update: vaccine coverage in England, January to March 2023 and 2022 to 2023 annual coverage. Health Protection Report volume 17 number 10, 17 August 2023