DOI: 10.12809/hkmj154626
Department of Paediatrics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong
Corresponding author: Prof KL Hon (
 Full paper in PDF
To the Editor—In 2003, the World Health Organization coined the word “SARS” for severe acute respiratory syndrome in patients with a relevant travel/contact history and severe acute respiratory symptoms.1 2 3 In 2012, the definition of SARS was not used when monitoring another outbreak of illness with the same symptoms and viral aetiology.3 4 5 Instead, the virus was termed the Middle East respiratory syndrome coronavirus (MERS-CoV) and “MERS” has since become the official nomenclature for the epidemic.3 In May 2015, a South Korean man travelled to Huizhou after first arriving in Hong Kong. His father had recently returned from Bahrain and was confirmed to have been infected with MERS. The case aroused panic about an outbreak of MERS beyond the Middle East in Korea, and possible outbreaks in Hong Kong and Mainland China. Meanwhile, the Hong Kong media colloquially referred to the MERS outbreak as the “new SARS”, despite the new official nomenclature.
MERS and SARS are the same syndrome in that both are caused by coronavirus, and are associated with fever, respiratory symptoms, and a relevant travel history (Table).5 In other words, the severity, acuteness, and respiratory syndrome in MERS is no less severe than SARS. There is no need to create a new name and abbreviation each time a coronavirus emerges.

Table. Comparison of SARS with MERS (initially termed SARI associated with coronavirus infection)
Some experts opine that MERS carries a higher mortality, and there is a travel or contact history linked with the Middle East.4 In 2012, the initial patients with MERS had non-respiratory (renal) involvement and the MERS-CoV differed to the SARS-CoV. On this basis, MERS and SARS are not the same.
Health organisations should provide consistent definitions for index surveillance and epidemiological and prognostication studies. They should resist the temptation to introduce unnecessary new terminology each time an outbreak of the same severe respiratory infection occurs.2 Diagnosis of emerging infections should be laboratory-based and not clinical or ‘syndrome’-based.
1. Hon KL, Leung CW, Cheng WT, et al. Clinical presentations and outcome of severe acute respiratory syndrome in children. Lancet 2003;361:1701-3. CrossRef
2. Hon KL, Li AM, Cheng FW, Leung TF, Ng PC. Personal view of SARS: confusing definition, confusing diagnoses. Lancet 2003;361:1984-5. CrossRef
3. Hui DS, Memish ZA, Zumla A. Severe acute respiratory syndrome vs. the Middle East respiratory syndrome. Curr Opin Pulm Med 2014;20:233-41. CrossRef
4. Zumla A, Hui DS, Perlman S. Middle East respiratory syndrome. Lancet 2015 Jun 3. Epub ahead of print. CrossRef
5. Hon KL. Severe respiratory syndromes: travel history matters. Travel Med Infect Dis 2013;11:285-7. CrossRef