The risk of measles outbreaks in London is significant, warned researchers, who urged doctors to be alert for symptoms of the disease.
The steps taken by a London hospital to protect patients and staff who were potentially exposed to the measles virus, and measures taken subsequently to prevent an outbreak of measles, were detailed at this year's European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) in Copenhagen, Denmark, which took place from 15-18 April.
The UK briefly achieved measles-free status in 2016/2017, but this status was lost in 2018. In February last year, UK data showed that vaccination coverage for young children had fallen in 2021 for 13 of 14 routine programmes across the UK and that since March 2020 there had been a significant reduction in uptake of MMR, with vaccination coverage at its "lowest level for a decade". Dr Doug Brown, chief executive of the British Society for Immunology, raised concern that this was "extremely worrying".
The authors of the new study "Re-emergence of measles and management of a mass exposure event" highlighted that the incidence of measles had been very low in the UK during the pandemic. In London, uptake of routine MMR vaccine dose one had been consistently below the 95% target set by the World Health Organisation, with MMR dose 2 at 5 years falling to 74.2% during 2021- 2022. This allowed a "significant risk of outbreaks", with pregnant women, infants, and severely immunosuppressed patients at highest risk, they warned.
Helen Bedford, professor of child public health at UCL's Institute of Child Health, recently commented that the UK risked facing "the concerning double whammy of many children being unprotected and the inevitability of disease rates increasing".
Dr David Harrington, Barts Health NHS Trust, London, and lead author, said: "We are already seeing signs that measles may be re-emerging in London. At Barts Health NHS Trust, we had five confirmed unrelated cases in February of this year." He pointed out that these cases were the "first to be detected" by their labs since early 2020.
He warned that "given the low vaccine uptake in London, the risk of outbreaks is significant".
Be Alert and Isolate Suspected Measles Cases Early
In their poster presentation, researchers from the Royal London Hospital, Barts Health NHS Trust, London, discussed the case study of a 28-year-old woman who presented to the emergency department in February this year "with a typical prodrome and rash consistent with measles, subsequently confirmed by PCR testing of a buccal swab".
The patient had been in the hospital emergency department waiting room for 8 hours before being isolated, and 103 patient contacts and eight staff contacts had been identified. Dr Harrington and his team took "rapid action" to contain a potential outbreak of the disease. This involved reviewing clinical notes to identify patient contacts at highest risk, performing measles IgG tests to establish immunity, and administering intravenous immunoglobulins where appropriate.
The female index case, who had not had the MMR vaccine, returned home after medical assessment and investigations.
Dr Harrington urged clinicians to be "alert to the signs of measles" and triage and "isolate suspected cases early". This would limit spread in healthcare environments and reduce exposure to those at high risk of severe outcomes, he explained.
"Many front-line clinicians won't have seen measles for several years, however, and so good education and training and collaboration between public health and infection specialists with those in primary and emergency care is key," he added.
"When exposure does occur, a risk assessment must be carried out immediately. Rigorous contact tracing is also essential," Dr Harrington stressed.
High MMR Coverage Crucial
The authors postulated that if all contacts could not be risk assessed, it might be more feasible to identify and risk assess those falling into high-risk groups only. Generic ‘warn and inform’ letters to all potential contacts may also be useful if resources are available to produce them, they suggested.
Human normal immunoglobulin is expensive and in short supply, cautioned the authors, who added that high coverage with two doses of MMR is a "more effective" way to protect vulnerable individuals within a general population.
In February this year, the WHO emphasised that to prevent a resurgence of measles urgent action was needed to identify all those who have missed vaccine doses, and to devise targeted catch-up strategies.
"It is important to remember that the MMR vaccine is highly effective in preventing measles with providing lifelong protection and I would urge parents to ensure their children are up to date with their vaccines," Dr Harrington said.
The material within the abstract presented has been peer reviewed by the congress selection committee, but there is no full paper at this stage.