Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a zoonotic betacoronavirus — first identified in Saudi Arabia in 2012 — that causes a severe respiratory illness in humans with a case fatality rate of approximately 35%. It is transmitted from dromedary camels to humans, with limited human-to-human transmission occurring primarily in healthcare settings. Despite causing fewer total cases than SARS or COVID-19, MERS-CoV's high case fatality rate and potential for nosocomial amplification make it a WHO R&D Blueprint priority.

How is MERS-CoV transmitted?

Zoonotic transmission (camel-to-human): direct contact with infected dromedary camels or their secretions (nasal, respiratory, excreta); consumption of raw camel milk or undercooked camel meat. Human-to-human: requires close unprotected contact — mainly in healthcare settings (MERS patients without PPE exposing healthcare workers) and households of infected patients. MERS-CoV does NOT transmit efficiently in the community — Ro <1. Key contexts: healthcare workers without adequate PPE; close family caregivers.

Why was the South Korea 2015 outbreak so severe?

A single patient who had travelled to Middle Eastern countries with camels was diagnosed with MERS-CoV in South Korea in May 2015. Due to delays in diagnosis and inadequate infection control, the patient was transferred between multiple healthcare facilities while infectious. The result: 186 cases, 38 deaths, 16,752 quarantined, major economic disruption. This outbreak demonstrated how a single MERS-CoV importation, combined with healthcare system lapses in infection prevention, can cause a large cluster far outside the Arabian Peninsula. South Korea subsequently implemented dramatically improved preparedness.

Who is at highest risk?

Severe MERS-CoV disease is concentrated in: older males with comorbidities; people with diabetes (the single most important risk factor — diabetics have dramatically worse outcomes); chronic renal disease (DPP4 receptor expressed in kidney); cardiovascular disease; and immunocompromised patients. Healthcare workers without adequate PPE are at high occupational risk during patient care. Secondary cases in healthcare settings have significantly lower mortality than primary cases — possibly reflecting shorter exposure or detection at an earlier disease stage.

How is MERS-CoV treated?

No specific antiviral or approved vaccine. Management is entirely supportive: supplemental oxygen; mechanical ventilation for ARDS; prone positioning; supportive renal replacement therapy; treatment of secondary infections. Multiple antivirals have been studied in vitro: lopinavir/ritonavir, remdesivir, ribavirin + interferon-alpha. MERS-CoV-specific monoclonal antibodies (REGN3048/3051, SAB-301) have been tested in early studies. No evidence-based antiviral recommendation exists. Strict infection prevention and control (contact, droplet and airborne precautions) in healthcare settings is the most critical intervention.

Is MERS-CoV a pandemic threat?

MERS-CoV currently does NOT spread efficiently person-to-person — Ro <1 prevents sustained community transmission. However, pandemic risk concerns arise from: the precedent set by COVID-19 (another betacoronavirus that acquired efficient human transmission); the potential for MERS-CoV to acquire mutations increasing human-to-human transmissibility; its extreme severity (35% CFR — far above COVID-19 or influenza); and the vast dromedary camel reservoir across three continents (Africa, Middle East, Central Asia) — providing ongoing zoonotic spillover opportunities. WHO, CEPI and national agencies prioritise MERS-CoV pandemic preparedness.

How does GMJ News cover MERS-CoV?

GMJ News covers WHO MERS-CoV situation reports, outbreak epidemiology, camel reservoir, nosocomial transmission prevention, vaccine development and pandemic risk assessment. MERS-CoV represents the ongoing threat of emerging coronaviruses — directly relevant to PHIG's health security programme and Georgia's infection prevention standards.

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MERS-CoV

Q: Why was the South Korea 2015 outbreak so severe?

A single patient who had travelled to Middle Eastern countries with camels was diagnosed with MERS-CoV in South Korea in May 2015. Due to delays in diagnosis and inadequate infection control, the patient was transferred between multiple healthcare facilities while infectious. The result: 186 cases, 38 deaths, 16,752 quarantined, major economic disruption. This outbreak demonstrated how a single MERS-CoV importation, combined with healthcare system lapses in infection prevention, can cause a large cluster far outside the Arabian Peninsula. South Korea subsequently implemented dramatically improved preparedness.

Q: Who is at highest risk?

Severe MERS-CoV disease is concentrated in: older males with comorbidities; people with diabetes (the single most important risk factor — diabetics have dramatically worse outcomes); chronic renal disease (DPP4 receptor expressed in kidney); cardiovascular disease; and immunocompromised patients. Healthcare workers without adequate PPE are at high occupational risk during patient care. Secondary cases in healthcare settings have significantly lower mortality than primary cases — possibly reflecting shorter exposure or detection at an earlier disease stage.

Q: How is MERS-CoV treated?

No specific antiviral or approved vaccine. Management is entirely supportive: supplemental oxygen; mechanical ventilation for ARDS; prone positioning; supportive renal replacement therapy; treatment of secondary infections. Multiple antivirals have been studied in vitro: lopinavir/ritonavir, remdesivir, ribavirin + interferon-alpha. MERS-CoV-specific monoclonal antibodies (REGN3048/3051, SAB-301) have been tested in early studies. No evidence-based antiviral recommendation exists. Strict infection prevention and control (contact, droplet and airborne precautions) in healthcare settings is the most critical intervention.

Q: Is MERS-CoV a pandemic threat?

MERS-CoV currently does NOT spread efficiently person-to-person — Ro <1 prevents sustained community transmission. However, pandemic risk concerns arise from: the precedent set by COVID-19 (another betacoronavirus that acquired efficient human transmission); the potential for MERS-CoV to acquire mutations increasing human-to-human transmissibility; its extreme severity (35% CFR — far above COVID-19 or influenza); and the vast dromedary camel reservoir across three continents (Africa, Middle East, Central Asia) — providing ongoing zoonotic spillover opportunities. WHO, CEPI and national agencies prioritise MERS-CoV pandemic preparedness.

Q: How does GMJ News cover MERS-CoV?

GMJ News covers WHO MERS-CoV situation reports, outbreak epidemiology, camel reservoir, nosocomial transmission prevention, vaccine development and pandemic risk assessment. MERS-CoV represents the ongoing threat of emerging coronaviruses — directly relevant to PHIG's health security programme and Georgia's infection prevention standards.

GMJ News knowledge hub · last reviewed October 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Middle East respiratory syndrome coronavirus (MERS-CoV) — a zoonotic virus transmitted from dromedary camels to humans — has caused 2,605 laboratory-confirmed human cases and 936 deaths since its discovery in 2012 (as of 2023), with a case fatality rate of approximately 35% — making it the most lethal known coronavirus (WHO). MERS-CoV is a WHO R&D Blueprint priority pathogen — with Saudi Arabia accounting for over 80% of cases, primarily through human-to-human nosocomial transmission. The 2015 South Korea outbreak (186 cases, 38 deaths from a single imported case) demonstrated MERS-CoV's potential to cause large healthcare facility outbreaks globally.

Key messages

35% case fatality — most lethal known coronavirus

MERS-CoV has caused 2,605 laboratory-confirmed cases and 936 deaths since 2012 — a case fatality rate of approximately 35% — making it the most lethal known coronavirus. Saudi Arabia accounts for over 80% of cases (WHO 2023).

Dromedary camels — the reservoir

MERS-CoV is a zoonotic coronavirus — with dromedary camels serving as the primary reservoir. Camels are infected asymptomatically and shed virus in nasal secretions. Human cases result from direct or indirect exposure to infected camels or their products.

Nosocomial amplification — the main threat

Human-to-human transmission of MERS-CoV is inefficient — but healthcare settings amplify outbreaks dramatically. The 2015 South Korea outbreak (186 cases, 38 deaths from a single imported case) demonstrated how a single undiagnosed MERS-CoV case in a hospital can trigger large nosocomial clusters.

WHO R&D Blueprint priority pathogen

MERS-CoV is on the WHO R&D Blueprint priority pathogen list — driving emergency vaccine and therapeutic development. Multiple MERS vaccines are in Phase 1-2 trials; no vaccine is currently approved.

Severe respiratory disease

MERS-CoV causes a spectrum from asymptomatic to severe ARDS requiring mechanical ventilation. Severe disease is most common in older adults and those with comorbidities (diabetes, renal disease, chronic lung disease). Case fatality in hospitalised patients approaches 40-50%.

No approved vaccine or treatment

No MERS-CoV vaccine or specific antiviral is approved. Supportive care (oxygen, mechanical ventilation) is the primary treatment. Monoclonal antibodies targeting the MERS-CoV spike protein are in clinical development.

Key statistics

2,605

confirmed MERS-CoV cases since 2012

WHO 2023

936

MERS-CoV deaths since 2012

WHO 2023

~35%

case fatality rate overall

WHO

>80%

of cases in Saudi Arabia

WHO

186

cases in South Korea 2015 outbreak (from 1 imported case)

WHO/CDC Korea

approved vaccines or antivirals for MERS-CoV

WHO 2024

MERS-CoV confirmed cases by country — cumulative since 2012 (WHO)

Source: WHO situation reports. Saudi Arabia dominates; South Korea 2015 outbreak was the largest outside the Arabian Peninsula.

Glossary of key terms

MERS-CoV
WHOMiddle East Respiratory Syndrome Coronavirus — a betacoronavirus (same genus as SARS-CoV and SARS-CoV-2) first identified in Saudi Arabia in 2012. Uses DPP4 (dipeptidyl peptidase 4) as its cell entry receptor — expressed in the lower respiratory tract (explaining severe respiratory disease) and kidney.

Dromedary camel reservoir
WHO/OIEDromedary camels (Camelus dromedarius) are the primary animal reservoir of MERS-CoV — infected asymptomatically and shedding virus in nasal secretions. MERS-CoV antibodies are near-universal in adult dromedaries across Africa, the Middle East and Central Asia. Bats are the suspected original source.

DPP4 receptor
ResearchDipeptidyl peptidase 4 (also called CD26) — the cell surface receptor that MERS-CoV spike protein binds to for entry. DPP4 is expressed highly in the lower respiratory tract and kidney (explaining predominant ARDS and renal failure in MERS). DPP4 receptor differences between bat, camel and human DPP4 explain species-specific tropism.

R naught (Ro) of MERS-CoV
WHOThe basic reproduction number of MERS-CoV in the general community is <1 (typically 0.5-0.8) — meaning sustained human-to-human community transmission does not occur. However, in healthcare settings with inadequate infection control, the effective reproduction number can be much higher — driving nosocomial outbreaks.

MERS-CoV clinical spectrum
WHO/ClinicalMERS-CoV infection ranges from asymptomatic (in approximately 21% detected through contact tracing) to mild febrile illness to severe pneumonia and ARDS requiring ICU admission. Risk factors for severe disease: older age; male sex; diabetes (dramatically increases severity); chronic kidney disease; cardiovascular disease; and immunocompromise.

MERS vaccine development
CEPI/WHOMultiple MERS-CoV vaccines are in Phase 1-2 clinical trials: ChAdOx1 MERS (Oxford/Vaccitech — adenoviral vector); MVA-MERS-S (spike protein); DNA vaccines; mRNA vaccines (Moderna). CEPI has funded MERS vaccine development. Platform vaccines developed for COVID-19 have accelerated MERS vaccine progress.