Research and analysis

Laboratory confirmed cases of measles, rubella and mumps in England: October to December 2023

Updated 3 May 2024

Applies to England

Measles, rubella and mumps are notifiable diseases and healthcare professionals are legally required to inform their local Health Protection Team (HPT) of all suspected cases. 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.

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 on ensuring 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 – and, importantly, discarding – suspected measles and rubella cases. 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 on the Rubella Nucleotide Surveillance (RubeNS) system, as appropriate, 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 second quarter of 2023 (October to December). Analyses are done by date of onset of rash or symptoms and regional breakdown figures relate to Government Office Regions.

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

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

Results from all samples tested at Colindale are reported on the MOLIS/LIMS system and reported back to the patient’s GP and local HPT.

Table 1. Total suspected cases of measles, rubella and mumps reported to HPTs: weeks 39 to 52 of 2023

Notified as	Number of suspected cases*	Per cent tested by OF [Target: 80% (measles and rubella only)]	Other samples received in Virus Reference Laboratory	Number of samples IgM positive or viral detection	Number locally confirmed	Discard rate based on negative tests per 100,000 population (all samples)**
Measles	1,256	49.8%	54	118	94	0.98
Rubella	71	26.8%	20	2	0	0.06
Mumps	1,494	50.7%	66	33	4	–

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

**The rate of suspected measles or rubella cases investigated and discarded as non-measles or non-rubella using laboratory testing in a proficient laboratory. The annual discard rate target set by WHO is 2 cases per 100,000 population. We present quarterly rates here with an equivalent target of 0.5 per 100,000 population. The discard rate is based on VRD testing only because local negative tests are not routinely reported to UKHSA.

Measles

In the period between October and December 2023, 212 laboratory confirmed cases of measles were reported in England, compared to 21 cases reported in the previous quarter (Figure 1) (1) bringing the total number of laboratory confirmed measles cases in England for 2023 to 362. The increase in the fourth quarter of 2023 was mainly driven by an outbreak in Birmingham [2] .

Analysis of data for the whole of 2023 (2) and provisional data for the early weeks of 2024 (3) has been published at Measles epidemiology 2023 and 2024.

Of the 212 laboratory confirmed cases in England in the fourth quarter of 2023 only 18 (8.5%) were imported and only 2 (0.9%) were import-related.

Forty one per cent of the confirmed cases (87 of 212) were in children under 5 years of age and 15.6% (33 of 212) were in 15 to 34 year-olds; 6.6% of fourth quarter cases (14 of 212) were previously vaccinated with at least one dose of the MMR vaccine.

There were 5 laboratory confirmed cases reported in Wales, and 1 imported case in Scotland which was epidemiologically linked to a cluster in Wales. No cases were reported in Northern Ireland between September and December 2023.

Figure 1. Laboratory confirmed cases of measles by month of onset of rash or symptoms reported, London and England: January 2012 to December 2023

Across the WHO Europe Region there has been an increase in measles infections, with cases reported in 41 countries between December 2022 and November 2023. The vast majority of cases were reported by Kazakhstan, the Russian federation and Kyrgyzstan (4).

Measles activity has also picked up globally with outbreaks affecting many parts of Africa and South East Asia. WHO Europe has warned that a resurgence of measles is now an imminent threat, particularly due to the fall in vaccination rates during the COVID-19 pandemic (5).

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. This quarter, an oral fluid sample was returned for only 49.8% of all suspected measles cases reported in England, well below the 80% WHO target (Table 1).

Mumps

In England, there were 37 laboratory-confirmed mumps infections in the period October to December 2023, the same as in the previous quarter (1).

Nine of the 37 cases (29%) this quarter were in children and young adults aged under 20 years; of these, 5 had been vaccinated.

Figure 2. Laboratory confirmed cases of mumps by quarter, England: January 2012 to December 2023

Rubella

This quarter, a case of Congenital Rubella Syndrome was confirmed in a newborn whose mother had an undetected infection during pregnancy. The infection in the mother has been confirmed retrospectively. In keeping with trends observed in the last 20 years (6), the mother was unvaccinated, not born in the UK and had recently entered the UK from a rubella-endemic country; however, she appears to have been in the UK at the time of her exposure.

This is the first laboratory-confirmed case of rubella in the UK since 2019.

References

1. UKHSA (2024). Laboratory confirmed cases of measles, rubella and mumps, England: July to September 2023. Health Protection Report: volume 18 number 5

2. UKHSA (2024). National Measles Standard Incident - measles epidemiology (from October 2023)

3. UKHSA (2024). Confirmed cases of measles in England by month, age and region: 2023

4. WHO Europe (2024). Measles and rubella monthly update: December 2023

5. US Centers for Disease Control and Prevention (2022). Progress toward regional measles elimination worldwide, 2000 to 2021. Mortality and Morbidity Weekly Report: volume 71, number 47, pages 1,489 to 1,495

6. PHE (2019). UK measles and rubella elimination strategy 2019