Research and analysis

Laboratory confirmed cases of measles, mumps and rubella in England: July to September 2024

Updated 20 December 2024

Applies to England

Introduction

Measles, mumps and rubella are notifiable diseases; healthcare professionals are legally required to inform their local health protection team (HPT) of any suspected case. National enhanced surveillance including oral fluid (OF) testing of all suspected cases is provided through the Virus Reference Department (VRD) at Colindale to support and monitor progress towards World Health Organization (WHO) measles and rubella elimination targets (1).

Two WHO indicators are of prime importance for measuring the performance of national measles and rubella surveillance systems. These are:

1. The rate of laboratory investigations (at least 80% of suspected cases).
2. The annual rate of discarded cases (at least 2 per 100,000 population).

In order to achieve these targets, the focus of the UK Health Security Agency (UKHSA) is to ensure that all suspected cases are appropriately tested. Immunoglobulin M (IgM) serology testing and oral fluid testing are the only tests considered adequate by WHO for confirming or discarding a suspected measles or rubella case. Recent infection is confirmed by measuring the presence of IgM antibodies or detecting viral RNA (by PCR) in these samples.

Samples that have been confirmed positive for measles or rubella in a proficient laboratory (this includes local laboratories as well as the National Reference Laboratory) are included in this report. Samples that are referred to, or tested at, the National Reference Laboratory are further sequenced and entered on the WHO global Measles Nucleotide Surveillance (MeaNS) or the Rubella Nucleotide Surveillance (RubeNS) system, respectively, which are hosted at the National Reference Laboratory. Genotyping and further characterisation of measles and rubella is used to support investigation of transmission pathways and sources of infection.

Data presented here is for the third quarter of 2024 (July to September). Analyses are executed using the onset date of a rash or, more broadly, symptoms, and regional breakdown figures relate to the Government Office Regions.

Historical annual and quarterly measles, mumps and rubella epidemiological data is available from 2013 onwards:

• Measles: confirmed cases
• Mumps: confirmed cases
• Rubella: confirmed cases

The results from all samples tested at Colindale are reported to our laboratory information system MOLIS. The results are then reported back to the respective general practitioner (GP) and local HPT. The local HPT reports all suspected cases of measles, mumps and rubella on HPZone.

Data caveats

Since the beginning of July 2024, UKHSA has been gradually phasing out HPZone and transitioning Health Protection Teams to a new platform, the Case Incident Management System (CIMS), to capture information on notifiable infections such as measles. CIMS has impacted on our ability to routinely extract data on foreign travel from the national surveillance system. As a result, this quarterly report does not include information on the proportion of measles cases that were imported. Work is underway to allow this information to be provided in future.

Overview

Table 1. Number of suspected cases of measles, mumps and rubella reported to HPTs with breakdown of: a) proportion tested by Oral Fluid (OF); b) other samples referred to the Virus Reference Department (VRD), Colindale, from local NHS hospital and private laboratories; c) cases confirmed at the VRD; d) cases confirmed at regional, local NHS hospital and private laboratories; e) discard rate (measles and rubella only): weeks 27 to 40 of 2024

Notified as	Total suspected cases*	Number (%) tested by OF**	Other samples received by VRD	Number of samples IgM positive or viral detection in VRD	Number locally confirmed	Discard rate based on negative tests per 100,000 population (all samples)***
Measles	1,871	648 (34.6)	302	549	55	2.20
Mumps	933	399 (42.3)	49	10	7	1.59
Rubella	52	29 (55.8)	2	0	0	–

*This represents all cases reported to HPTs in England; that is: possible, probable, confirmed and discarded cases on HPZone and CIMS.

**The target set by WHO is 80% for measles and rubella only.

***The WHO has set a target for the annual discard rate of 2 cases per 100,000 population, which translates to a quarterly target of 0.5 per 100,000. It should be noted that we have proportionally adjusted the annual target, to ensure there is consistent testing across each quarter. This ensures we regularly achieve the target, rather than batch testing in one quarter to achieve the annual discard rate. The discard rate is based on VRD testing only because local negative tests are not routinely reported to UKHSA. Therefore, this is likely to be an underestimation of the true discard rate.

Measles

There was a rapid increase in measles cases in late 2023 driven by a large outbreak in Birmingham, with subsequent rises in London and small clusters in other regions. In the period between July to September 2024, there were 612 laboratory confirmed cases of measles reported in England, a decrease of approximately 40% compared to the previous quarter (n=1,086) (2) (Figure 1). The cases this quarter were mainly driven by outbreaks in London, East of England and South East regions. Details of the latest epidemiology linked to the national incident are available (3).

The majority of cases – 57.2% (350 of 612) – were in children aged 10 years or younger; 3.3% of cases (20 of 612) were previously vaccinated with one dose of the MMR vaccine and 3.8% (23 of 612) with at least two doses.

10 laboratory confirmed measles cases were reported in Northern Ireland, 23 in Scotland and 2 in Wales during the third quarter of 2024.

Figure 1. Laboratory confirmed cases of measles by month of onset of rash or symptoms reported, London and England: January 2012 to September 2024

Cases of measles in the WHO Europe Region cases began to rise in early 2022, and this has continued into 2024 (4). More cases were reported in the first 6 months of 2024 than in all of 2023. Cases were reported in 49 (92%) countries from the region between September 2023 and August 2024 (5), decelerating progress towards measles elimination (4). In the period September 2023 to August 2024, most cases were reported by Kazakhstan (n=38,522), Azerbaijan (n=30,379) and the Russian Federation (n=21,977) (5). Notably, measles incidence in 2024 has also been very high in Romania (622 per 1,000,000) (6). Measles activity is also increasing across WHO Africa, Eastern Mediterranean and South-East Asian Regions (7).

All suspected cases of measles and rubella should be reported promptly to HPTs, a risk assessment conducted and an Oral Fluid Kit (OFK) sent for confirmatory testing even if local diagnostic testing is underway. The WHO has set an 80% target for testing of suspected measles cases. In this quarter, there was a further decrease in the OF return rate, to 36% from 43% in the previous quarter (2), well below the WHO target (Table 1).

Mumps

In England, there were 17 laboratory confirmed mumps infections in the period between July to September, a reduction of 60% since the last quarter (n=43) (2).

It is important to note that the case decrease since last quarter may be in part due to:

i) a temporary pause in the issuing of OFKs to suspected mumps cases in the South East region between May and September 2024; an estimated 300 notified cases did not receive an OFK during this period

ii) a delay in the issuing of OFKs to suspected mumps cases in the London region between July and September 2024, which may have impacted test outcomes; an estimated 36 notified cases that did not receive an OFK during this period.

Of the 17 mumps cases, 2 (11.8%, 2 of 17) cases were in those aged under 15 years, with the majority (88.2%, 15 of 17) in those aged 15-years-and-over. Only 1 individual had received a single dose of the MMR vaccine and 3 had received two doses. The remaining cases had no vaccine recorded.

Figure 2. Laboratory confirmed cases of mumps by quarter, England: January 2012 to September 2024

Rubella

There were no laboratory confirmed cases of rubella reported in this quarter.

References

1. PHE (2019). UK Measles and rubella elimination strategy 2019

2. UKHSA (2024). ‘Laboratory confirmed cases of measles, rubella and mumps in England: April to June 2024’. Health Protection Report volume 18 number 8

3. UKHSA (November 2024). ‘Confirmed cases of measles in England by month, age, region and upper tier local authority: 2024’

4. Muscat M, Ben Mamou M, Reynen-de Kat C, Jankovic D, and others (2024). ‘Progress and challenges in measles and rubella elimination in the WHO European Region’. Vaccines: volume 12, number 6.

5. WHO Europe (October 2024). ‘Measles and rubella monthly update: September 2024’

6. WHO Europe (2024). Measles/rubella (MR) dashboard.

7. US Centers for Disease Control and Prevention (2024). Global Measles Vaccination – Global Measles Outbreaks.