Pertussis (whooping cough) surveillance and epidemiology

Epidemiology

Pertussis incidence typically has a cyclical pattern with peaks in cases every three to four years. The peak prior to 2012 in England and Wales was in 2008, with 902 laboratory confirmed cases (PHE, 2013). In 2012, there was a significant increase in the number of pertussis cases reported in the UK (Kmietowicz, 2012), USA (Centers for Disease Control and Prevention, 2015), New Zealand (Institute of Environmental Science and Research Ltd, 2012) and Australia (Government of Western Australia, 2012). In Wales, there were 358 confirmed cases in 2012, 26 cases were in infants under one year of age of which 21 were aged under three months (PHE, 2013). Infants under one year of age are the group most susceptible to serious complications.

During 2013 and 2014 the number of confirmed pertussis cases in Wales decreased before rising again in 2015 and 2016. During 2017 and 2018 the number of confirmed cases decreased to 171 and 112 respectively before increasing again in 2019 to 182 confirmed cases. Most cases are in adults. Laboratory confirmations of pertussis in infants aged under one by year have fallen steadily since 2015, especially in infants under 3 months of age.

Pertussis in Wales: 2010-2023

Notifications

Laboratory confirmations

Source: Confirmation data from UKHSA reference laboratory
Year	Number of cases	Rate per 100,000 population
2010	14	0.46
2011	73	2.38
2012	358	11.65
2013	200	6.49
2014	115	3.72
2015	285	9.20
2016	255	8.19
2017	171	5.47
2018	112	3.57
2019	182	5.77
2020	37	1.17
2021	10	0.32
2022	6	0.19
2023	73	2.30

Rate per 100,000 population and number of confirmed cases of pertussis in Wales from 2010-2023

Confirmed cases of pertussis in Wales by age

Year	under 3 months	3 to 5 months	6 to 11 months	1-4	5-9	10-14	15-24	25-34	35-44	45-64	65+	All ages
2010	2	0	0	0	0	2	3	2	2	3	0	14
2011	25	0	1	2	2	1	7	7	11	15	2	73
2012	21	4	1	3	4	24	47	46	74	109	25	358
2013	6	2	0	1	7	21	26	22	37	62	16	200
2014	3	0	1	2	6	14	14	17	15	26	17	115
2015	10	2	1	13	18	36	31	30	45	69	30	285
2016	8	2	1	4	9	27	22	31	54	66	31	255
2017	5	1	1	2	4	12	17	16	31	57	25	171
2018	4	0	1	4	5	9	8	11	17	36	17	112
2019	0	0	1	8	15	19	9	20	27	57	26	182
2020	0	0	1	2	3	3	5	2	5	13	3	37
2021	0	0	0	0	0	0	0	0	4	4	2	10
2022	0	0	0	0	0	1	0	0	2	1	2	6
2023	1	0	3	4	5	13	7	5	8	15	12	73

Confirmed pertussis cases in 2019-2023 by quarter of onset

Quarter	Number of cases in 2019	% of 2019 year total	Number of cases in 2020	% of 2020 year total	Number of cases in 2021	% of 2021 year total	Number of cases in 2022	% of 2022 year total	Number of cases in 2023	% of 2023 year total
Jan-Mar	30	16.5	29	78.4	2	20	1	16.7	0	0
Apr-Jun	35	19.2	6	16.2	1	10	2	33.3	13	17.8
Jul-Sep	60	33	2	5.4	2	20	0	0	29	39.7
Oct-Dec	57	31.3	0	0	5	50	3	50	31	42.5

Immunisation against pertussis

Pertussis is a vaccine preventable disease. The pertussis vaccine is included in the DTaP/IPV/Hib/HepB ‘6-in-1 jab’ given to babies at 2, 3 and 4 months.

As immunity against pertussis wanes over time, a booster vaccination has also been included in the ‘4-in-1’ pre-school boosters (given between 3-5 years of age) with the aim of reducing illness in older age groups thereby reducing transmission of pertussis to unvaccinated or partially vaccinated babies.

Due to the considerable increase in the rates of pertussis during 2011/12, a vaccination programme was established to offer pertussis vaccination to all expectant mothers in the UK from week 16 of pregnancy. This is to help protect their newborn infants from whooping cough until they are old enough to receive their routine immunisations which start from 8 weeks of age.

Uptake and coverage of all recommended childhood immunisations are monitored and reported by Public Health Wales quarterly and annually at local and national levels in the COVER (Coverage of Vaccination Evaluation Rapidly) report. This is published on both a quarterly and annual basis.