Editor's Note: This article was updated to reflect that the WHO shared confirmed fatality rate -- not mortality rate.

The World Health Organization (WHO) on Tuesday said the confirmed fatality rate of COVID-19, the disease caused by SARS-CoV-2 remained at 3.4%.

WHO Director-General Tedros Adhanom Ghebreyesus described SARS-CoV-2 as "a unique virus, with unique features. This virus is not influenza. We are in uncharted territory."

Coronavirus.

Image source: Getty Images

Numerous comparisons have been made between influenza -- aka, the flu -- and COVID-19. They share similar symptoms, and both spread rapidly among populations. Influenza, however, is far less deadly, with a confirmed fatality rate of only 0.1%.

The coronavirus continues to spread. In the U.S., according to the latest figures, there are 149 confirmed cases. On Wednesday, the 11th U.S. fatality was reported -- an elderly person in Placer County, California. Meanwhile, the second case on the East Coast has been confirmed -- an unidentified man who commuted to work in Manhattan from his home in neighboring Westchester County, New York.

Against this backdrop, more pharmaceutical companies and biotechs continue to join the fight. On Wednesday, Alnylam Pharmaceuticals (NASDAQ:ALNY) and Vir Biotechnology (NASDAQ:VIR) announced they will expand their partnership and attempt to jointly develop treatments for SARS-CoV-2. That project will center on RNA interference therapeutics. Alnylam and Vir have been collaborating on other treatments since 2017.

Shares of Alnylam and Vir both closed notably higher on Wednesday, with the former increasing by just over 5% and the latter by nearly 10%. The S&P 500 closed the day 4.2% higher.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.