Novavax Inc said its coronavirus vaccine was 89.3% effective in preventing COVID-19 in a trial conducted in the United Kingdom, and was nearly as effective in protecting against the more highly contagious variant first discovered in the UK, according to a preliminary analysis.
A mid-stage trial of the vaccine in South Africa, where a troubling new variant of the virus is common, showed 60% effectiveness among people who did not have HIV.
Novavax shares surged 34% in after hours trading following release of the trial results on the same day the United States reported its first cases of the South African variant.
Novavax is already stockpiling vaccine at six operating manufacturing locations, and said it expects a total of eight plants in seven countries to produce at the rate of 2 billion doses per year, including from the Serum Institute of India.
The company on a conference call noted that this was interim data and executives said they expect it will be two to three months before they are ready to apply for authorization with regulators.
The UK trial, which enrolled 15,000 people aged 18 to 84, is expected to be used to apply for use in Britain, the European Union and other countries.
Approval of the Novavax vaccine would be most welcome in Europe as it struggles with meager vaccine supply after Pfizer/BioNTech and AstraZeneca Plc delivered fewer doses than hoped.
Executives on the call said the company was discussing with the U.S. Food and Drug Administration whether the UK and South Africa data was enough to apply for U.S. emergency use authorization.
The UK study took place as the more highly transmissible UK variant was circulating. The preliminary analysis suggests the vaccine was 85.6% effective against this mutation, the U.S. company announced in its news release. It did not provide detailed data.
In the UK trial, the effectiveness of the vaccine was close to that of the two authorized vaccines from Pfizer Inc with BioNTech SE and Moderna Inc, whose two-dose regimens were both around 95% effective at preventing COVID-19 in clinical trials.