Research and analysis

Laboratory confirmed cases of measles, rubella and mumps in England: April to June 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 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 second quarter of 2023 (April to June). 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:

• 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 13 to 25 of 2023

Notified as	Number of suspected cases*	Number (%) tested by OF. [Target: 80% (measles and rubella only)]	Other samples received in Virus Reference Laboratory	Number of samples IgM positive or viral detection	Discard rate based on negative tests per 100,000 population (all samples)**
Measles	686	346 (50%)	55	85	0.55
Rubella	63	23 (37%)	9	0	0.06
Mumps	1,413	715 (51%)	74	36	–

*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.

Measles

In the period between January and June 2023, 91 laboratory confirmed cases of measles were reported in England compared to 31 cases reported in the previous quarter (Figure 1) (1). Of these 91 cases:

• 9 (10%) were imported and 3 (3%) were import-related; a slight decrease from 23% and 10% in the previous quarter, respectively (1), reflecting an increase in community transmission of measles
• 36% of the confirmed cases (33 out of 91) were in children aged under 5 years
• 18% (16 of 91) were in those aged 15 to 34 years; a decrease from 38% in the previous quarter (1)
• 9% (8 out of 91) of the cases were previously vaccinated with at least one dose of the MMR vaccine
• 1 laboratory confirmed case in Wales, in a child aged under one year, was travel-related

No cases were reported in Scotland or Northern Ireland between January and June 2023.

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

In response to the increasing number of confirmed measles infections in England, UKHSA issued a Briefing Note for health professionals in May, highlighting key actions for HPTs and the NHS (2).

In July, the UKHSA published a measles risk assessment that showed that due to sub-optimal levels of immunisation coverage, London could sustain an outbreak of between 40,000 and 160,000 cases (3).

Outside of London the risk of large measles outbreaks is low but smaller outbreaks could be seen in specific populations, including teenagers, young people and under-vaccinated communities. NHS England has launched a targeted national campaign to encourage uptake of the MMR vaccine, including targeted outreach work in London for those identified as at high risk and communities with the lowest uptake of vaccination.

Across the WHO Europe Region there has been an increase in measles infections, with cases reported in 36 countries and numbers had exceeded the total for 2022 by the end of February. Between July 2022 and June 2023, the vast majority of cases were reported in the Russian federation, Tajikistan and Turkey (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 50% of all suspected measles cases reported in England, well below the 80% WHO target (Table 1).

Mumps

In England, there were 36 laboratory-confirmed mumps infections in the period January to June 2023 – compared to 51 between January and March 2023 (1).

Fourteen of the 36 cases (39%) this quarter were in children and young adults aged under 20 years. Of these, only 3 (8%) were vaccinated.

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

Rubella

There have been no new laboratory confirmed cases of rubella reported in the UK since 2019.

References

1. UKHSA (2023). Laboratory confirmed cases of measles, rubella and mumps, England: January to March 2023. Health Protection Report: volume 17 number 9

2. UKHSA (2023). Update on UK measles epidemiology and actions to prevent a measles resurgence. Health Protection Report: volume 17 number 5

3. UKHSA (2023). RIsk assessment for measles resurgence in the UK.

4. WHO Europe (2022). Measles and rubella monthly update: April 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