Measles

Measles infection in Northern Ireland

1 Summary

  • From 1 January 2024 to 16 June, 137 clinically suspected measles cases have been notified to the Public Health Agency.
  • Of those notified during 2024 to 16 June, eleven were laboratory confirmed.
  • A Northern Ireland measles, mumps and rubella (MMR) vaccination catch-up campaign is currently running to increase protection against the virus among children aged 12 months up to and including twenty-five years of age.

2 Background

Measles is a systemic viral infection caused by the measles virus. It is normally characterised by a fever, rash and respiratory illness. For more information about measles please visit NI Direct | Measles.

A vaccine against measles, which also provides protection against mumps and rubella (MMR), is included in the Northern Ireland childhood vaccination schedule at one year of age and at three years and four months. From February 2024, anyone in Northern Ireland aged from one to twenty-five years, who has not already had two doses of MMR, is also eligible to receive the vaccine as part of a regional ‘catch-up’ campaign. For more information please visit NI Direct | MMR catch-up campaign, NI Direct | MMR and NI PHA | MMR vaccine catch-up.

Public and clinician awareness of measles has changed over time, especially during February 2024, which may contribute to changes in trends.

Details of case definitions and methods are at the end of this document. Data were correct at 16 June 2024.

3 Measles notifications, 2023-2024

The number of notified clinically suspected measles cases from the start of 2023 until the report date are shown (Table 3.1).

Table 3.1: Counts of measles notifications, 2023-2024.
2023 2024
(N=19) (N=137)
Case category
Confirmed 0 (0%) 11 (8.0%)
Probable 0 (0%) 22 (16.1%)
Possible 19 (100%) 104 (75.9%)

Please note: in the table above data for 2024 is up to 16 June

4 Discussion

There have been eleven laboratory confirmed cases during 2024, the first since 2017. There was an increase in notifications of clinically suspected measles during February 2024, likely due to increased awareness and reporting. There is an increased risk of measles outbreaks due to a reduction in MMR vaccine coverage in Northern Ireland during recent years NI PHA | MMR vaccine coverage. Increasing coverage of the MMR vaccine is crucial to ensure widespread protection and prevent outbreaks of measles.

5 Methods

Measles notifications are reported by clinicians to the Public Health Agency and were extracted from the case management database. Measles is notifiable in Northern Ireland under the Public Health Act (1967) Northern Ireland.

Cases are presented by the date that they were recorded on the PHA database. Notified cases will be removed from future reports if PHA is notified that clinical investigations later result in an alternative diagnosis. Numbers may therefore reduce.

Data were processed in R.

5.1 Measles Case Definitions

Confirmed case: A case with laboratory confirmation of acute infection.

Probable case: A case with clinically classical symptoms of measles AND no previous MMR vaccinations or history of previous infection AND at least one of the following risk factors:

  • Travel history in last 21 days.
  • Attendance at large international mass gathering events.
  • The case is a member of a community/population associated with low MMR vaccine uptake or measles outbreaks. Note this may only apply when there is transmission in Northern Ireland.

Possible case: A case with clinically classical symptoms of measles AND zero, one or two doses of MMR vaccine BUT no additional risk factors including those listed above.

The above case definitions are based on the current situation in Northern Ireland (as of 21 March 2024) and are subject to change.

6 Supplementary Table

Case category Total
Confirmed Probable Possible
Week of Report



2024-01-01 0 0 1 1
2024-01-08 0 0 1 1
2024-01-15 0 0 1 1
2024-01-22 0 0 2 2
2024-01-29 0 1 1 2
2024-02-05 0 1 2 3
2024-02-12 1 1 5 7
2024-02-19 1 9 12 22
2024-02-26 0 5 12 17
2024-03-04 0 1 7 8
2024-03-11 0 1 7 8
2024-03-18 0 0 9 9
2024-03-25 0 0 6 6
2024-04-01 0 0 2 2
2024-04-08 1 1 4 6
2024-04-15 2 0 2 4
2024-04-22 1 0 5 6
2024-04-29 5 0 2 7
2024-05-06 0 0 4 4
2024-05-13 0 0 8 8
2024-05-20 0 0 3 3
2024-05-27 0 1 5 6
2024-06-03 0 1 0 1
2024-06-10 0 0 3 3
Total 11 22 104 137