Research and analysis

Laboratory confirmed cases of pertussis in England: April to June 2022

Updated 23 May 2024

Applies to England

In England, there were 15 laboratory confirmed cases of pertussis (culture, PCR, serology or oral fluid (OF)) reported to the UK Health Security Agency (UKHSA) pertussis enhanced surveillance programme in the second quarter of 2022, from April to June (Table 1). Total case numbers were 67% higher than those reported in same quarter of 2021 (9 cases). However, the number of laboratory confirmed cases in this quarter was 89% lower than in the second quarter of 2020 (133 cases) and considerably lower than the 969 cases reported in the quarter, pre-pandemic, of 2019 (see Figure 1 and Table 2).

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 (1). From July 2021, COVID-19 containment measures were withdrawn in England. Vaccination continues to be important as levels of disease are likely to increase following the easing of control measures.

Overall pertussis activity declined after measures to control the spread of COVID-19 were introduced and laboratory-confirmed cases remain low following the cessation of control measures. The number of confirmed cases in infants under 3 months, who are targeted by the maternal immunisation programme, continues to remain extremely low with one confirmed case in this quarter compared to 0, 13 and 23 cases in the same quarters in 2021, 2020 and 2019, respectively.

There were no confirmed cases in infants aged between 3 and 11 months, consistent with protection from primary vaccination offered at 2, 3 and 4 months. There were 6 confirmed cases in children aged between 1 and 4 years compared to 2 and 10 cases in 2021 and 2020, respectively. Overall, there was one case in infants aged less than one year in the second quarter of 2022 compared to 0 and 21 in the equivalent quarters in 2021 and 2020, respectively (Table 2).

Between April and June 2022, 7 of the 15 cases of laboratory confirmed pertussis in England occurred in individuals aged 15 years or older. The total in this age group was also low in the same period in 2021 at 7 cases, compared to 133 cases in April to June 2020 and 681 cases reported in the same quarter, pre-pandemic, of 2019.

Guidelines for the public health management of pertussis provide details on the appropriate laboratory investigation of suspected cases of pertussis which is informed by the age of the suspected case and time since onset of their symptoms. Investigation of those with clinical presentation consistent with pertussis should be undertaken, in line with this guidance.

Deaths

There were no reported deaths in infants with pertussis confirmed in April to June 2022. The last pertussis-related death of an infant was reported in the second quarter (April to June) of 2019. Calculated maternal vaccine effectiveness against death of infants from pertussis is very high at around 97% (2).

Childhood vaccination programme

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 (evaluated between January and March 2022) for DTaP/IPV/Hib/hepB immunisation across England was 91.9% for 3 doses at 12 months of age and 84.6% for the booster dose by 5 years of age (3). Coverage estimates at 12 months of age were slightly higher than the coverage estimates for January to March 2021 when the proportion of children vaccinated at 12 months was 91.6% and coverage estimates for the booster dose were lower than the 85.1% 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 introduced in response to the 2012 outbreak (5, 6) became permanent from June 2019 (7) based on evidence of disease impact, high effectiveness and safety (2, 8, 9, 10). 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 for pragmatic reasons to ensure vaccination (7).

Monthly pertussis vaccine coverage was 61.5% in April, 60.4% in May and 61.5% in June 2022. The mean coverage for the quarter was 60.6%, which was 3.9 and 8.9 percentage points lower than mean coverage for the same quarters in 2021 and 2020, respectively (11). This observed decline in coverage has largely been driven by a decrease in London NHS commissioning region which had coverage that was 15.2 percentage points lower in June 2022 as compared to June 2020 (11).

The impact of the pandemic on healthcare services has possibly resulted in vaccine coverage this quarter being lower than any previous quarter since 2016 (11). This could be due to a potential increase in the delivery of the vaccines through maternity units during the pandemic, which may not have been captured completely in the survey and therefore resulted in an underestimation of coverage.

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 (2). COVID-19 control measures appear to have had an additional impact on these observed effects. It is therefore important that women continue to be supported to access immunisation against pertussis during pregnancy (ideally between 20 and 32 weeks) to optimise protection for their babies from birth.

Table 1. Laboratory-confirmed cases of pertussis, by age and testing method, in England: April to June 2022

Age group Culture PCR Serology Oral fluid only Total
Less than 3 months 0 1 0 0 1
3 to 5 months 0 0 0 0 0
6 to 11 months 0 0 0 0 0
1 to 4 years 0 2 2 2 6
5 to 9 years 0 0 0 0 0
10 to 14 years 0 0 0 1 1
15 years and over 0 0 7 0 7
Total 0 3 9 3 15

*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.

Figure 1. Total number of laboratory-confirmed pertussis cases per quarter in England, 2011 to 2022 (Q1 and Q2)

Table 2. Laboratory-confirmed cases of pertussis, by age and year, in England: April to June, 2012 to 2022

Age group 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Less than 3 months 118 25 26 31 50 26 10 23 13 0 1
3 to 5 months 16 12 1 4 16 12 7 8 6 0 0
6 to 11 months 5 4 2 4 6 6 3 8 2 0 0
1 to 4 years 12 8 8 14 33 21 15 29 10 2 6
5 to 9 years 36 19 37 48 82 77 42 65 7 0 0
10 to 14 years 216 119 89 138 157 124 82 155 22 0 1
15 years and over 1,294 933 647 719 1,104 931 521 681 73 7 7
Total 1,697 1,120 810 958 1,448 1,197 680 969 133 9 15

References

1. Tessier E and others (2022). ‘Impact of the COVID-19 pandemic on Bordetella pertussis infections in England’. BMC Public Health: volume 22, number 405

2. Amirthalingam G and others (2023) ‘Optimization of timing of maternal pertussis immunization from 6 years of post-implementation surveillance data in England’, Clinical Infectious Diseases: volume 76, issue 3

3. Quarterly vaccination coverage statistics for children aged up to 5 years in the UK (COVER programme): January to March 2022. Health Protection Report: volume 16, number 6 (28 June 2022)

4. Quarterly vaccination coverage statistics for children aged up to 5 years in the UK (COVER programme): January to March 2021. Health Protection Report: volume 15, number 6 (29 June 2021)

5. Confirmed pertussis in England and Wales continues to increase (2012). Health Protection Report: volume 6 number 15

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 minutes

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 new-born infants in England and Wales, 2012–2013’, Clinical Infectious Diseases

10. Donegan K and others (2014) ‘Safety of pertussis vaccination in pregnant women in UK: observational study’, British Medical Journal

11. Pertussis vaccination programme for pregnant women update: vaccine coverage in England, April to June 2022. Health Protection Report: volume 16, number 12 (29 November 2022)