Novavax said its coronavirus vaccine was 90% effective at preventing COVID-19.
The shot succeeded in a study that enrolled almost 30,000 volunteers in the US and Mexico.
The Maryland biotech plans to ask US regulators for permission to give the shot more widely.
The biotech company Novavax said on Monday that its coronavirus vaccine succeeded in a final-stage clinical trial, demonstrating 90% efficacy at preventing COVID-19.
Novavax had previously announced results from smaller studies in the UK and South Africa that suggested its two-dose vaccine worked. Data from the larger study will allow Novavax to submit the shot to US regulators. The company plans to file by the end of September.
The biotech disclosed the success in a press release and said it planned to submit more-detailed results to a scientific journal. The press release didn't specify whether Novavax planned to file for emergency-use authorization or full approval with regulators.
Coronavirus vaccines developed by Moderna, Pfizer and BioNTech, and Johnson & Johnson have already been authorized in the US. Nearly 65% of the adult population has received at least one dose, and more than 143 million people in the US are fully vaccinated, according to the Centers for Disease Control and Prevention.
If Novavax's vaccine wins a US OK, it would be a major victory for the biotech, which has never produced an authorized medicine in its 33-year history.
It remains to be seen how the Novavax vaccine will be used in the US immunization campaign. AstraZeneca's shot has faced similar questions, and the pharma giant still hasn't applied for an OK with the US Food and Drug Administration.
Novavax's vaccine was highly effective against variants and in protecting vulnerable groups
Novavax's late-stage clinical trial recruited 29,960 volunteers in the US and Mexico. Two-thirds of the volunteers were randomly assigned to receive two doses of Novavax's vaccine. The other third received placebo injections and served as a control group.
Overall, 77 cases of COVID-19 were observed among these study volunteers: 63 in the placebo group and 14 in the group that got the vaccine. That suggests Novavax's vaccine was 90.4% effective at preventing symptomatic illness. All 14 COVID-19 cases among people who got the vaccine were mild.
Novavax also said the shot was 100% effective at preventing moderate to severe disease. Fourteen of the COVID-19 cases in the placebo group were moderate or severe.
Researchers also sequenced most of the cases reported in the study to determine which strain of the coronavirus was responsible. The company said the vaccine was about 93% effective in preventing illnesses caused by variants of concern or variants of interest.
Among the most vulnerable population - including older people and those with frequent exposure to the virus - Novavax's vaccine was 91% effective.
The study found no safety concerns, with the most common side effects being injection-site pain, fatigue, headache, and muscle pain. These were typically mild to moderate in severity and lasted no longer than two to three days, the company said.
Delays raise questions on Novavax's path to widespread use, profits
Last month, Novavax disclosed a delay in its plans to file for an emergency OK, pushing its application from the second quarter to the third quarter of 2021. The company said it was still in the final stages of confirming its manufacturing processes with regulators.
Despite the uncertainty surrounding its use in the US, Novavax's COVID-19 vaccine program has been a remarkable and unlikely success story. Headed into 2020, the biotech firm was on the verge of bankruptcy, reeling from a late-stage study failure for an experimental vaccine against respiratory syncytial virus.
Novavax's stock price started 2020 at about $4 a share. Spurred by its COVID-19 vaccine work, as well as success with a flu-shot program, the company climbed to a record-high $22 billion valuation in February, trading at more than $300 a share. Novavax shares closed last week at $209.68, giving the company a market value of $15.5 billion.
To supporting its coronavirus work, the biotech has nearly quadrupled in size, growing to 791 full-time employees from 165 in the past year. Last week, corporate executives unveiled plans to massively expand its headquarters in Gaithersburg, Maryland, with plans to build a new 180,000-square-foot plant focused on vaccine research.
The US government has funded Novavax's research, committing to pay $1.6 billion to the biotech last summer to run this late-stage study and purchase 100 million doses. Novavax also received financial support from the Coalition for Epidemic Preparedness Innovations, a Bill Gates-backed nonprofit, which provided up to $388 million in funding to Novavax last spring to support its vaccine research.
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