Novavax Inc. surged the most in six years after its vaccine helped elderly patients in a mid-stage study fend off a potentially lethal respiratory virus.
The vaccine reduced the risk of the disease associated with lower respiratory infection by 46 percent when compared with a placebo in 1,600 patients aged 60 and older, according to a statement late Monday. The shares rose 24 percent to $13.89 at the close in New York on Tuesday, giving Novavax a market value of $3.75 billion.
There are currently no approved vaccines to prevent respiratory syncytial virus, or RSV, which kills about 14,000 American adults over 65 every year, according to the U.S. Centers for Disease Control and Prevention. About 4.9 percent of participants who received the placebo showed symptoms of RSV, the study found. Treating RSV in the elderly is Novavax’s largest opportunity, according to Joel Beatty, an analyst at Citigroup Inc.
“The vaccine is protecting people from the beginning to the end of the season, so it’s durable,” Greg Glenn, Novavax’s head of research and development, said by phone. The efficacy rate, helping roughly half of test subjects, was “right in there” with other vaccines approved by regulators, Glenn said. Influenza vaccines range in effectiveness between a 10 percent to 60 percent reduction in doctors’ visits for flu.
The company said the treated patients had about the same side effects as those given a placebo, without disclosing specifics. Novavax plans to start a large-scale trial by November if it receives necessary regulatory approvals, Chief Executive Officer Stan Erck said by phone, with data available by summer of 2016.
“I believe it will exceed the world’s largest-selling vaccine,” Erck said. Glenn said the targeted population would include all adults over 60. There will be about 55 million Americans 65 and older in the U.S. by 2020, according to the U.S. Census Bureau.
Larger companies are also in the hunt for a vaccine against RSV. GlaxoSmithKline Plc is studying a vaccine to prevent the disease in children, as is AstraZeneca Plc’s Medimmune business. Medimmune already produces a drug to prevent lung disease caused by RSV in children.
Novavax, headquartered in Gaithersburg, Maryland, is also working on vaccines for Ebola, influenza strains and the Middle East Respiratory Syndrome coronavirus, according to its website.
(An earlier version of this story corrected spelling of the company’s name.)