MERS left the Middle East for the first time since 2019 — twice, in one week in France

MERS has spent most of the last six years as a domestic problem in the Arabian Peninsula. That is not a description of the virus changing; it is a description of where the camels are, and of who travels.

On 24 December, the World Health Organization published a global update reporting that between 2 and 3 December, France's International Health Regulations focal point notified two cases of MERS-CoV in people with recent travel to the Arabian Peninsula during November [s1].

The significance is in the comparison. WHO's May 2025 update on MERS stated that since 2019, no human MERS-CoV infections had been reported from countries outside the Middle East [s2]. France has recorded four laboratory-confirmed cases in total since September 2012, including one death: two in 2013, and these two in December 2025 [s1]. All four were travellers exposed in the Arabian Peninsula [s1].

The year, in numbers

Since the beginning of 2025 and as of 21 December, 19 MERS-CoV cases including four deaths were reported to WHO globally [s1]. Seventeen came from Saudi Arabia, across five regions: Riyadh (10), Taif (3), Najran (2), Hail (1) and Hafr Al-Batin City (1) [s1]. Two were the travel-associated cases in France [s1].

The December update focuses on the nine cases reported between 4 June and 21 December: seven from Saudi Arabia, including two deaths, from Najran (2), Riyadh (3) and Taif (2), with no epidemiological links identified between them, plus the two imported to France [s1].

Against the full history, the year is small. Since the first reports in Saudi Arabia and Jordan in 2012, 2,635 laboratory-confirmed cases and 964 associated deaths have been reported to WHO from 27 countries across all six WHO regions [s1]. Saudi Arabia accounts for 84% of cases — 2,224, with 868 deaths, a case fatality ratio of 39% [s1]. The global case fatality ratio stands at 37% [s1].

What happened in France

Genomic sequencing from the first French case identified the same lineage circulating in the Arabian Peninsula [s1]. Contact tracing was initiated as soon as the first case was detected, covering fellow travellers and co-exposed individuals, high-risk contacts and hospital contacts [s1].

It was completed in week 51. No additional cases were reported among the travellers and no secondary cases as of 19 December [s1]. Asymptomatic co-exposed individuals and at-risk contacts in France were offered a full testing protocol — nasopharyngeal swab, sputum, rectal swab and serology — on a voluntary basis up to 29 days after last exposure, whether or not they had symptoms [s1].

That is an intensive response to two imported cases, and the reason for it is in the record. MERS transmits between people mainly in health-care settings, and it does so when cases are recognised late [s1]. The 2015 outbreak in the Republic of Korea produced 186 laboratory-confirmed cases — 185 in Korea and one in China — and 38 deaths, from a single index case with a travel history to the Middle East [s1].

The clusters that show why surveillance intensity matters

Saudi Arabia has reported three limited health-care-associated clusters recently: two in 2024, of three and two cases, and one in 2025 of seven cases [s1]. Before those, the previous cluster was in May 2020 [s1].

The 2025 cluster is the instructive one. WHO's May update described it: seven cases identified in Riyadh, six of them health and care workers who acquired the infection while caring for a single infected patient [s2]. Four of the six health workers were asymptomatic and two had only mild, non-specific symptoms — myalgia, fatigue, nausea and vomiting [s2]. All were found through contact tracing and testing of contacts, and all recovered [s1][s2].

Only one of the nine cases reported in Saudi Arabia between 1 March and 21 April 2025 had even indirect contact with camels, and that case was not part of the cluster; the rest had no known history of contact with camels or camel products [s2].

Six asymptomatic or mildly symptomatic infections in health workers were detected because somebody went looking. In a country that had not added MERS-CoV to its sentinel testing algorithm — Saudi Arabia has included it for samples testing negative for both influenza and SARS-CoV-2 since the second quarter of 2023 [s1] — none of them would have appeared in any count.

A note on the numbers themselves

The two updates do not reconcile arithmetically, and the discrepancy is worth stating rather than smoothing over.

WHO's May update put the global total at 2,627 cases and 946 deaths as of 21 April 2025 [s2]. The December update puts it at 2,635 cases and 964 deaths as of 21 December [s1]. That is eight additional cases but eighteen additional deaths, over a period in which the December update describes nine new cases and two new deaths [s1].

WHO's own caveat covers the mechanism: the total number of deaths includes those officially reported to WHO based on follow-up with affected member states, and case totals may underestimate the true number if infections were not reported, went untested because they resembled other circulating respiratory illness, or were asymptomatic or mild [s1][s2]. Deaths among previously counted cases being confirmed retrospectively is the most likely explanation. It is also a reminder that these are reconciled surveillance totals, not a live count.

The risk assessment, and what is still missing

WHO states that the notification of these cases does not change the overall risk assessment, which remains moderate at both global and regional levels [s1]. It expects additional cases from the Middle East and other countries where MERS-CoV circulates in dromedaries, and expects cases to continue being exported by people exposed through camels, camel products or health-care settings [s1].

There is no vaccine and no specific treatment; management is supportive [s1]. Several MERS-specific vaccines and therapeutics are in development [s1].

The therapeutic evidence base is thin enough to summarise in two sentences. The largest clinical trial in MERS compared lopinavir–ritonavir plus interferon β-1b with placebo in 95 patients, finding 90-day mortality of 48% with placebo and 29% with active treatment, with further analysis suggesting benefit only in patients treated within seven days of symptom onset [s1]. A retrospective analysis of 349 MERS patients found no difference in 90-day mortality among the 136 who received macrolide antibiotics [s1].

Incubation is typically 2 to 15 days, median 5, with longer periods reported in immunocompromised patients [s1]. WHO does not advise special screening at points of entry, nor any travel or trade restrictions in relation to this event [s1].

What to watch

Whether further exported cases follow the French pair, and whether the number of Saudi cases with no identifiable camel exposure — which was eight of nine in the spring cluster period [s2] — continues to grow, since that is the pattern that would signal transmission chains surveillance is not seeing.

This article is informational and is not medical advice.

Sources

• [s1] World Health Organization. "Middle East respiratory syndrome coronavirus - Global update." Disease Outbreak News, 24 December 2025. https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON591
• [s2] World Health Organization. "Middle East respiratory syndrome coronavirus - Kingdom of Saudi Arabia." Disease Outbreak News, 12 May 2025. https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON569