Research and analysis

Laboratory confirmed cases of pertussis in England: October to December 2021

Updated 6 July 2022

Applies to England

In England, there were 20 laboratory confirmed cases of pertussis (culture, PCR, serology or oral fluid) reported to the UK Health Security Agency (UKHSA) pertussis enhanced surveillance programme in the fourth quarter of 2021, from October to December (table 1). Total case numbers were the same as those reported in the fourth quarter of 2020 (figure 1).

The coronavirus (COVID-19) pandemic and the implementation of social distancing measures and lockdown across the UK from 23 March 2020 has 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 From July 2021 COVID-19 containment measures were withdrawn in England.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 continues to be important as levels of disease are likely to increase as control measures have eased.

Overall pertussis activity has declined since measures to control the spread of COVID-19 were introduced. The number of confirmed cases in infants under 3 months, who are targeted by the maternal immunisation programme, continues to remain extremely low with 1 confirmed case in this quarter compared to 0 and 19 cases in the same quarter in 2020 and 2019, respectively.

There were also no confirmed cases in infants aged between 1 and 4 years. Overall there was 1 confirmed cases in an infants aged less than one year in the fourth quarter of 2021 whilst there were no cases in the equivalent period in 2020 and 27 in 2019 (table 2).

Between October and December 2021, 15 of the 20 cases of laboratory confirmed pertussis in England occurred in individuals aged 15 years or older, 1 case was aged between 5 and 9 years, and 3 cases were aged between 10 and 14 years.

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.

Deaths

There were no reported deaths in infants with pertussis confirmed between October and December 2021. 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 in their infant from pertussis is very high at around 95% (1).

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 October and December 2021) for DTaP/IPV/Hib/HepB immunisation across England was 92.0% for 3 doses at 12 months of age and 84.2% for the booster dose by 5 years of age (2).

Coverage estimates at 12 months of age were slightly higher than the coverage estimates for October to December 2020 when the proportion of children vaccinated at 12 months was 91.5% and coverage estimates for the booster dose were lower than the 85.4% reported (3).

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 (4, 5) became permanent from June 2019 (6) based on evidence of disease impact, high effectiveness and safety (1, 7, 8, 9). 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 (6).

Monthly pertussis vaccine coverage was 65.7% in October, 65.0% in November and 65.4% in December 2021. The mean coverage for the quarter was 65.3%, which was 6.7 percentage points lower than the same quarter in the 2019 (10).

The impact of the pandemic on healthcare services has possibly resulted in vaccine coverage this quarter to be lower than any previous October to December coverage estimates since 2016. 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. COVID-19 control measures appear to have had an additional impact on these observed effects.

It is important that women continue to be supported during the ongoing pandemic to access immunisation against pertussis during pregnancy (ideally between 20 and 32 weeks) to optimise protection for their babies from birth.

Figure 1. Total number of laboratory-confirmed pertussis cases per quarter in England, 2011 to 2021

Table 1. Laboratory-confirmed cases of pertussis by age and testing method* in England, October to December 2021

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	0	0	0	0
5 to 9 years	0	0	0	1	1
10 to 14 years	0	0	1	2	3
15 years and over	0	1	14	0	15
Total	0	2	15	3	20

*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.

Table 2. Laboratory-confirmed cases of pertussis by age and year in England, October to December: 2012 to 2021

Age group	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021
Less than 3 months	72	13	13	32	21	18	15	19	0	1
3 to 5 months	10	1	4	4	10	7	4	5	0	0
6 to 11 months	5	0	1	2	5	3	3	3	0	0
1 to 4 years	45	24	21	20	27	15	19	30	2	0
5 to 9 years	59	24	34	56	50	32	26	41	1	1
10 to 14 years	240	47	84	88	100	57	68	95	4	3
15 years and over	3,018	638	725	923	1,149	791	579	740	13	15
Total	3,449	747	882	1,125	1,362	923	714	933	20	20

References

1. Amirthalingam G and others (2016) ‘Sustained effectiveness of the maternal pertussis immunization program in England three years following introduction’, Clinical Infectious Diseases

2. 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

3. Quarterly vaccination coverage statistics for children aged up to 5 years in the UK (COVER programme): October to December 2020. Health Protection Report volume 15 number 7, 30 March 2021

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

5. Department of Health (2012) Pregnant women to be offered whooping cough vaccine (website news story, 28 September)

6. Joint Committee on Vaccination and Immunisation minutes

7. Amirthalingam G and others (2014) Effectiveness of maternal pertussis vaccination in England: an observational study, The Lancet

8. 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

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

10. Pertussis vaccination programme for pregnant women update: vaccine coverage in England, October to December 2021. Health Protection Report volume 16 number 3 (22 February 2022)