Antiviral agents and corticosteroids in the treatment of severe acute respiratory syndrome (SARS)

The epidemic of severe acute respiratory syndrome (SARS) of 2003 caught the medical profession by surprise. The accumulated global total number of cases was 8098 with 774 deaths, a case-fatality ratio of 9.6%.¹ Although the novel coronavirus (SARS-CoV) was discovered within weeks,² treatment was inevitably empirical as controlled clinical trials were not possible during the epidemic of this new and serious illness. Many antiviral and immunomodulatory drugs, as well as other treatments such as convalescent patient plasma and traditional Chinese medicines, have been tried. Ribavirin and corticosteroids are by far the most widely used treatments for SARS. In the later phase of the epidemic lopinavir and ritonavir in combination were also used in Hong Kong.

ANTIVIRAL AGENTS

Ribavirin

Ribavirin is used extensively for the treatment of SARS and was given to over 90% of patients in Hong Kong. It is a nucleoside analogue that has activity against a number of DNA and RNA viruses in vitro.³ The mechanism of action of ribavirin has been studied for decades and is still under active debate.⁴ In early March 2003, before the isolation of the SARS-CoV, many experts believed that the mysterious severe illness was due to an unknown virus and ribavirin was empirically given because of its broad spectrum antiviral activity. Furthermore, corticosteroids were increasingly prescribed for the treatment of SARS and some believed that such treatment would be dangerous if not covered with an antiviral agent. The published reports on the effectiveness of ribavirin were mostly retrospective case series with intrinsic methodological issues and it is difficult to draw conclusions. The major side effect of ribavirin is anaemia which occurs in 27–59% …