Persistent signals from MERS-CoV in 2025: surveillance gaps, clinical heterogeneity, and preparedness priorities

More than a decade after its emergence, Middle East respiratory syndrome coronavirus (MERS-CoV) continues to cause sporadic but clinically significant infections [1]. Cases reported between June and December 2025 by the Kingdom of Saudi Arabia (KSA) and France [2] reaffirm that MERS-CoV remains a global health concern, characterized by persistent zoonotic transmission, severe outcomes among vulnerable populations, and the potential for international spread.

As in previous years, most cases occurred in KSA, particularly in Riyadh, Taif, and Najran, emphasizing the Arabian Peninsula's role as the epicenter of MERS-CoV activity. As previously reported [3], clinical presentations ranged from mild upper respiratory illness to severe pneumonia and death. Respiratory symptoms—fever, cough, and dyspnea—predominated, but atypical presentations, including isolated rhinitis, were also documented. This heterogeneity continues to complicate clinical recognition, particularly outside endemic settings.

Older age and comorbidities were strongly associated with poor outcomes [4]. All fatal cases occurred in older adults, and most severe cases involved patients with underlying conditions, consistent with global MERS-CoV epidemiology. Importantly, one fatal case occurred in an older individual without reported comorbidities, highlighting age as an independent risk factor.

Exposure histories pointed to dromedary camels and camel products as the principal zoonotic source [5,6,7]. Clear exposure was documented in several cases, including the imported cases in France linked to camel product consumption and animal market visits. However, multiple cases in KSA reported no known camel contact, a recurring observation that suggests underrecognized indirect exposure, environmental contamination, or health-care–associated transmission.

Several MERS-CoV patients were diagnosed post-admission for unrelated conditions, underscoring ongoing hospital surveillance limitations. This reflects absent symptoms during the virus incubation period, plus surveillance limitations, detection challenges, atypical presentations, testing delays, or prolonged asymptomatic shedding [8,9]. These factors contribute to the difficulty of tracking such sporadic cases. Delayed onset of MERS enables asymptomatic admission, with in-hospital symptom development fueling nosocomial clusters—where healthcare transmission surpasses community spread fourfold. Mild indicators often escape notice in non-respiratory cases, exacerbated by high pre-symptomatic viral loads [10,11]. Hospitals must adopt tiered admission screening (mandatory 14-day travel/exposure questions), daily fever/respiratory/rash monitoring, risk-based cohorting, and staff training via real-time dashboards. These steps boost early detection efficiently amid persistent MERS risks.

Although no health-care workers were affected, delayed recognition increases the risk of nosocomial transmission—a defining feature of past MERS outbreaks [12]. While RT-PCR confirmation was prompt once samples were obtained, delays between symptom onset and testing were notable in fatal cases, reinforcing the importance of early clinical suspicion. The infrequent and unpredictable transmission of MERS-CoV in Saudi Arabia has limited the effectiveness of incorporating testing into routine SARI protocols, as cases remain rare and sporadically distributed. MERS-CoV continues to demonstrate significant genetic stability, a characteristic that distinguishes it from more rapidly evolving coronaviruses like SARS-CoV-2 [13]. While minor variations exist, the core genomic structure remains remarkably consistent across different regions and host species. While current Infection Prevention and Control (IPC) measures in Saudi Arabia have successfully prevented massive nosocomial outbreaks, the recent 2025 data highlight that a shift toward high-impact healthcare case finding is necessary to address any “silent” transmission gaps. The detection of imported cases in France highlights the predictable nature of international spread. Mild or atypical presentations in travelers emphasize the need for continued clinical awareness and robust diagnostic capacity in non-endemic countries. Taken together, these cases illustrate that MERS-CoV has not disappeared but persists as a low-level, high-impact threat. Sustained surveillance, strengthened infection prevention and control, improved exposure assessment, and renewed investment in research on vaccines and therapeutics remain essential components of global preparedness.

Key MERS-CoV preparedness recommendations align with authoritative WHO and ECDC guidance, translating global standards into practical hospital-level operational actions (Table 1) [2,14]. Core strategies emphasize enhanced SARI surveillance in endemic areas, low-threshold testing for new respiratory symptoms in hospitalized patients, and robust IPC measures including tiered precautions and regular drills. Exposure history collection—particularly indirect camel contact—standardizes case investigations, while non-endemic countries maintain diagnostic readiness through clinical alerts and travel screening.

Table 1.

Harmonized MERS-CoV preparedness framework: WHO/ECDC alignment and actionable steps.

Recommendation	WHO guidance	ECDC guidance	Operational actions for implementation
Enhance surveillance among patients with severe acute respiratory infection (SARI) in endemic areas	WHO surveillance for human infection with MERS-CoV; WHO global surveillance standards for respiratory viruses	ECDC Rapid Risk Assessment: MERS-CoV	Integrate MERS-CoV testing into routine SARI surveillance; Ensure timely notification of confirmed cases to national authorities and WHO; Periodically review SARI testing algorithms
Apply a low threshold for testing hospitalized patients who develop new or unexplained respiratory symptoms	WHO clinical management of SARI when MERS-CoV is suspected; WHO IPC guidance during health care	ECDC guidance for prevention and control of respiratory infections in hospitals	Implement inpatient alert systems for new respiratory symptoms; Enable rapid access to RT-PCR testing; Isolate suspected cases pending confirmation
Strengthen infection prevention and control (IPC) in health-care settings	WHO IPC guidance for epidemic- and pandemic-prone ARIs; WHO health-care facility preparedness checklist for MERS-CoV	ECDC IPC and preparedness for COVID-19 and other respiratory viruses	Apply standard, contact, droplet, and airborne precautions as indicated; Conduct regular IPC training and simulation exercises; Ensure availability of PPE and isolation facilities
Improve systematic collection of exposure histories, including indirect camel contact	WHO public health surveillance for MERS-CoV; WHO risk communication and community engagement for zoonotic diseases	ECDC expert opinion on zoonotic respiratory viruses	Standardize exposure questionnaires (direct, indirect, environmental); Train surveillance staff in detailed exposure assessment; Integrate exposure findings into case investigations
Maintain clinical awareness and diagnostic capacity in non-endemic countries	International Health Regulations (2005); WHO travel advice on MERS-CoV	ECDC preparedness planning for emerging respiratory viruses	Maintain laboratory readiness for MERS-CoV diagnostics; Disseminate clinical alerts to frontline clinicians; Routinely assess travel and exposure history
Advance research and preparedness for future MERS-CoV threats	WHO R&D Blueprint for action to prevent epidemics	ECDC strategic framework for preparedness and response	Expand genomic surveillance of MERS-CoV; Support research on vaccines and therapeutics; Evaluate targeted protection strategies for high-risk groups

Operational implementation focuses on practical steps: integrating MERS-CoV RT-PCR into routine protocols, inpatient alert systems with rapid isolation, PPE stockpiling, and genomic surveillance expansion (Table 1). Staff training on exposure questionnaires and simulation exercises bridges policy to practice, addressing known gaps in nosocomial transmission where healthcare spread exceeds community cases fourfold. The framework supports future threats by linking research priorities (vaccines, therapeutics) to high-risk group protection, ensuring scalable preparedness amid MERS-CoV persistent endemicity and mutation potential.

CRediT authorship contribution statement

Jaffar A. Al-Tawfiq: Conceptualization, Investigation, Methodology, Supervision, Writing – original draft, Writing – review & editing. Abdullah M. Assiri: Writing – review & editing, Conceptualization.

Ethical approval statement

This is an editorial and does not require an ethical approval.

Funding source

None.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.