Research and analysis

HPR volume 18 issue 1: news (1 and 26 February 2024)

Updated 25 April 2024

Update on pertussis activity in England

In England, there were 856 (provisional) new laboratory confirmed cases of pertussis reported to the UK Health Security (UKHSA) pertussis enhanced surveillance programme in 2023.

Intervention measures implemented to help control the spread of COVID-19 between March 2020 and July 2021 additionally had an impact on other infectious diseases, including pertussis. Consequently, pertussis activity has been exceptionally low across England since April 2020 and persisted at low levels until Summer 2023 when case numbers began to increase (Figure 1), although overall numbers remained lower than pre-pandemic years (Figure 2, Table 1). The recent increase in pertussis cases has been observed across all regions in England and case numbers are expected to continue to rise in 2024.

Figure 1. Laboratory confirmed cases of pertussis by month in England: 2018 to 2023 (provisional data)

Of the 856 cases confirmed in 2023, more than half (452 cases, 52.8%) were in those aged 15 years or older and 20.4% were in children aged between 10 and 14 years (175 cases) (Table 2).

The number of confirmed cases in infants under 3 months, who are at most risk of severe disease and too young to be fully vaccinated, increased from 2 cases in 2022 to 48 cases in 2023 but remain lower than pre-pandemic years; there were 83 cases in infants under 3 months in 2019 (Table 2). Incidence continues to be highest in infants under 3 months (Figure 2).

Figure 2. Laboratory confirmed cases of pertussis by age group in England: 2018 to 2023 (provisional data)

Table 1. Laboratory confirmed cases of pertussis by reporting month in England: 2023 (provisional data)

Month	Total number of cases reported	Cumulative total of cases for 2023
January	9	9
February	9	18
March	12	30
April	20	50
May	33	83
June	53	136
July	72	208
August	93	301
September	102	403
October	102	505
November	111	616
December	240	856

Table 2. Laboratory confirmed cases of pertussis by age group in England: 2023 (provisional data)

Age group	2018	2019*	2020	2021	2022	2023
Under 3 months	49	83	30	1	2	48
3 to 5 months	26	32	15	1	3	23
6 to 11 months	17	21	5	0	0	25
1 to 4 years	87	147	49	3	11	54
5 to 9 years	139	222	52	2	3	79
10 to 14 years	288	467	150	3	3	175
15 years and over	2,342	2,706	693	39	47	452
Total	2,948	3,680	994	49	69	856

*Excludes 2 cases where the age was not known.

In the 12 years prior to the introduction of maternal pertussis vaccination in October 2012, 63 deaths occurred in babies aged under 1 year with confirmed pertussis. In the 12 years since the introduction of pertussis vaccination in pregnancy, there have been 21 deaths in babies with confirmed pertussis who were too young to be fully protected by infant vaccination. Only 2 of the 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. Calculated maternal vaccine effectiveness against death in their infant from pertussis is very high at around 97% (1).

Vaccine uptake levels in pregnant women, babies and young children have fallen in recent years across England. Maternal vaccine uptake fell from over 70% in September 2017 to around 58% in September 2023. Vaccination in pregnancy is key to passively protecting babies before they can be directly protected by the infant vaccine programme. Pertussis vaccination is recommended in every pregnancy between 20 and 32 weeks, ideally after the 20-week scan, but can be given as early as 16 weeks for pragmatic reasons to ensure vaccination. It is also important that babies are vaccinated on time wherever possible when they become eligible for infant doses at 8, 12 and 16 weeks of age and that those who miss vaccination are caught up at the earliest opportunity.

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. Appropriate confirmatory testing allows the situation to be closely monitored, ensures public health action is undertaken where needed and supports appropriate clinical management.

Reference

1. Amirthalingham G, Campbell H, Ribeiro S, Stowe J, Tessier E, 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.

HIV and viral hepatitis monitoring among PWID: annual report in summary

The UK Health Security Agency (UKHSA) has published new data from the Unlinked anonymous monitoring (UAM) survey of people who inject drugs (PWID) covering England, Wales and Northern Ireland for the period 2013 to 2022. This news report summarises the main findings.

The UAM survey is an annual, cross-sectional bio-behavioural survey recruiting PWID through drug and alcohol services across England, Wales, and Northern Ireland (EWNI). Prevalence data is available for HIV, hepatitis C virus (HCV) (antibodies and RNA) and hepatitis B virus (HBV) (antibodies to HBV core antigen and HBV surface antigen), alongside self-reported data for risk and protective behaviours.

In 2022, recruitment to the UAM survey recovered to pre-pandemic levels with 3,165 participants recruited.

Overall, prevalence of chronic hepatitis C (hepatitis C ribonucleic acid (RNA) and antibody positive) continues to decline, from 49% in 2017 to 23% in 2022 among people with antibodies to HCV (see figure). This decline is noted alongside the scale-up of direct-acting antiviral (DAA) treatment for hepatitis C virus (HCV) in the PWID population. However, decreases in chronic HCV prevalence are not similar across all nations and regions of England. There is no evidence to suggest a decline in chronic HCV prevalence among people who have recently started injecting drugs (up to 3 years prior to survey participation), which implies prevention of new and re-infections remains a challenge.

The proportion of UAM survey participants with HCV antibodies (a marker of ever HCV infection) has increased significantly over the past decade (from 49% in 2013 to 54% in 2022) and is higher in the older cohort. This likely reflects the impact of increased treatment uptake, in those recruited to the UAM who are ever-infected living longer.

Reflective of an ongoing outbreak in Northern Ireland, among UAM survey participants recruited in the country, HIV and HCV antibody prevalence has increased, from 0.9% and 29% in 2019 to 3.8% and 48% respectively in 2022. Additionally, reported recent injection of powdered cocaine surged from 5.9% in 2018 to a remarkable 84% in 2022.

Prevalence of chronic Hepatitis C (RNA-positive) among people with antibodies to HCV in the UAM survey of PWID (EWNI): 2013 to 2022

Risk behaviours are still prevalent, highlighting the need for focus on harm reduction. Direct sharing of injecting equipment has increased from 16% in 2013 to 19% in 2022. Although 82% of all PWID in the UAM survey reported that they had accessed a needle exchange in 2022, this is a notable decline from the 90% reported pre COVID-19 pandemic. Self-reported HBV vaccination uptake has also declined over the past decade from 72% in 2013 to 61% in 2022, suggesting decreasing immunity in PWID and increased susceptibility to HBV infection. In 2022, HBV vaccine uptake was particularly low among those aged under 25 years (27%) and people who have recently started injecting drugs (39%).

In 2022, nearly a quarter of those who had injected drugs in the past year reported experiencing a non-fatal overdose during that year, an increase from 16% in 2013.

Further data outputs from the UAM such as HIV and HBV prevalence, testing uptake and naloxone carriage and use are available in the published report.

The latest data release comprises two publications:

• a set of data tables titled: ‘Data tables for Unlinked Anonymous Monitoring (UAM) survey of HIV and viral hepatitis among PWID: 2023’
• a short accompanying report titled: ‘Unlinked Anonymous Monitoring (UAM) Survey of HIV and viral hepatitis among people who inject drugs (PWID): 2023 report’

Both the above publications are available on the webpage People who inject drugs: HIV and viral hepatitis monitoring.

TB cases rise in England

Figures published by UKHSA in its TB annual report show that tuberculosis cases in England in 2022 were stable compared to 2021 (4,380 in 2022 compared to 4,411 in 2021) (see figure below).

However, additional provisional data indicate that cases of tuberculosis (TB) in England rose by 10.7% in 2023 compared to 2022 (4,850 compared to 4,380). The rise signals a rebound of TB cases to above the pre-COVID-19-pandemic numbers.

While England remains a low incidence country for TB, the current trajectory takes the UK further from the pathway to meet World Health Organization (WHO) 2035 elimination targets. UKHSA is working with partners to investigate the reasons behind the increase in TB.

TB notifications (and notification rate per 100,000) in England: 1971 to 2022

Relocation of UK SMI web pages

The UK Standards for Microbiology Investigations (UK SMIs) are a comprehensive referenced collection of recommended algorithms and procedures for diagnostic and public health microbiology laboratories in the United Kingdom, the product of collaborative efforts by working groups of laboratory-based medical and scientific microbiologists from UKHSA and the NHS.

On 30 October 2023, hosting of the UK SMI web pages was transferred to the relevant pages on the Royal College of Pathologists (RCPath) website and the previously active UK SMI collection on GOV.UK was decommissioned on 12 December 2023.

For further information, email: standards@ukhsa.gov.uk.

Vaccine coverage reports in this issue

Prenatal pertussis vaccination coverage in England from July to September 2023

Infection reports

Acquired carbapenemase-producing Gram-negative bacteria in England: October 2020 to September 2023

Laboratory surveillance of Enterococcus spp. bacteraemia (England): 2022

Group A streptococcal infections: second update on seasonal activity in England, 2023 to 2024

Acute hepatitis B (England): enhanced surveillance reports, 2022

Hepatitis A (England and Wales): 2021