Laboratory confirmed cases of pertussis in England: July to September 2021

Question 1

Deaths

Accepted Answer

There were no reported deaths in infants with pertussis confirmed between July and September 2021. The last pertussis related death of an infant was reported in the second quarter (April to June) of 2019.

Of the 20 infants who have died following confirmed pertussis disease and who were born after the introduction of the maternal programme (on 1 October 2012); 18 were born to mothers who had not been immunised against pertussis during pregnancy. Calculated maternal vaccine effectiveness against death in their infant from pertussis is very high at around 95% (1).

Question 2

Childhood vaccination programme

Accepted Answer

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 July to September 2021) for DTaP/IPV/Hib/HepB immunisation across England was 91.3% for 3 doses at 12 months of age and 84.0% for the booster dose by 5 years of age which were slightly lower than the coverage estimates for July to September 2020 when the proportion of children vaccinated at 12 months was 92.1% and 85.4% for the booster dose.

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 these modest decreases.

Question 3

Maternal vaccination programme

Accepted Answer

The maternal pertussis immunisation programme introduced in response to the 2012 outbreak (2, 3) became permanent from June 2019 (4) based on evidence of disease impact, high effectiveness and safety (1, 5, 6, 7).

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 (4).

Monthly pertussis vaccine coverage ranged across the quarter from 64.5% in September to 65.4% in July. The mean coverage for the quarter was 64.9%, which was 1.8 percentage points lower than mean coverage for the same quarter in 2020 and 4.3 percentage points lower than mean coverage for the same quarter in the 2019 (8).

The impact of the pandemic on healthcare services has possibly resulted in vaccine coverage this quarter to be lower than any previous July to September 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.

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

Age group	Serology	Oral fluid only	Total
Less than 3 months	0	0	0
3 to 5 months	0	0	0
6 to 11 months	0	0	0
1 to 4 years	1	0	1
5 to 9 years	0	1	1
10 to 14 years	0	0	0
15 years and over	7	0	7
Total	8	1	9

*PCR confirmed cases may have additionally tested positive by serology or OF and serology confirmed cases may also have been confirmed by OF. Submission of all presumptive B. pertussis isolates is encouraged for confirmation of identity and to allow further characterisation for epidemiological purposes.