Chinese University of Hong Kong Researchers Compare SARS-CoV-2 & SARS & the Results may Surprise

Apr 25, 2020 | Chinese University of Hong Kong, COVID-19, Novel Coronavirus, Retrospective Study, SARS


Researchers from the Chinese University of Hong Kong compared case fatality ratios (CFR) and predictors of COVID-19 and SARS patients using a territory-wide cohort in Hong Kong. They sought to aid health professionals understand the comparisons and contrasts between the novel coronavirus (COVID-19) and severe acute respiratory syndrome (SARS)—two infectious diseases caused by the coronaviruses—SARS-CoV-2 and SARS-CoV respectively.

The Study

The Hong Kong-based researchers used data from the Clinical Data Analysis and Reporting System (CDAS) under the management of the Hospital Authority of Hong Kong. By making use of ICD-9-CM diagnosis codes and/or virological results, the team sought to identify laboratory-confirmed cases of COVID-19 and SARSs with a primary endpoint of Intensive Care Unit (ICU) admission, use of invasive mechanical ventilation, and/or death.

Key Data

Of the 114 COVID-19 patients (mean age 57.3 years, 50.0% male) identified for purposes of this study—diagnosed from January 8 to March 20, 2020 while they reviewed 1,670 SARS patients (mean age 44.4 years, 44.0% male) in March to June 2003.

COVID-19 (Jan 22 to March 8, 2020)

The study data reveals that out of the COVID-19 data, 11.4% of the patients had ICU admission; 7% of patients had to get invasive mechanical ventilation intervention while 3.5% of the COVID-19 patients died in just 30 days. By the 53rd day of the outbreak on March 15, 2020, four patients died (CFR, 3.5%).

SARS (March to June 2003)

Of the SARS data, the researchers uncovered that 25.9% of these patients were required to go into ICU admission while just under 20% require the use of invasive mechanical ventilation within 30 days. By June 30, 2003, 286 patients had passed (CFR, 17.1%).

The Findings

Although the perception is that COVID-19 is far more deadly—and that is true as it turned into a pandemic while the first SARS was contained to a regional epidemic—the findings here suggest that from a per capital basis, the first coronavirus was significantly more dangerous than the second one. According to the interpretation, COVID-19 is associated with approximately 55% lower risk of adverse clinical outcomes, compared to SARS post adjustment for clinical parameters. Nonetheless, the outbreak of COVID-19 pandemic unfolds in real-time, with growing numbers of COVID-19 patients worldwide. The absolute death count will be enormous, reports the Hong Kong researchers. 


This study has considerable limitations given that in reality, the data sets are extremely different. The first coronavirus was contained as an epidemic while the novel coronavirus outbreak has turned into a pandemic now centering on the United States. With 2.9 million total cases reported worldwide, the U.S. reports 952,995 as of this writing with 53,745 fatalities.

According to the CDC, the first coronavirus outbreak (SARS) about 8,098 became sick, and of that amount 774 died (9.5%). The outbreak stopped by the end of July as no more cases were being reported. Hence the first coronavirus represented an epidemic while the novel coronavirus that the world’s people face now is a pandemic.

Given the scale and magnitude of the pandemic, the Chinese University of Hong Kong researchers emphasize the importance of intensive care facilities and the need to protect them from being over run with cases and a collapse of healthcare systems. Hence the need for programs such as lock-downs, social distancing, and other proactive protective measures.

Chinese University of Hong Kong

Established in 1963, this public research university in Shatin, Hong Kong was granted a charter by the Legislative Council of Hong Kong. It is the territory’s largest university and was founded as a federation of three existing colleges including Chung Chi College, New Asia College, and United College—the oldest of which was founded in 1949. The Chinese University of Hong Kong is also known as CHUK.

Lead Research/Investigator

Numerous authors were involved with this study and they can be seen here.

Source: SSRN


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