The drugmaker reports nearly 96 percent efficacy against original SARS-CoV-2 and says the vaccine works but less so against the South Africa variant.
Novavax Inc has said its coronavirus vaccine showed overall 89.3 percent efficacy in preventing Covid-19 in a trial conducted in the United Kingdom, showing strong protection against both original virus and the UK variant. 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 percent effectiveness among people who did not have HIV.
The study of 15,000 people in Britain is still underway. The interim analysis found 62 participants so far have been diagnosed with Covid-19 – only six of them in the group that got vaccine and the rest who received dummy shots.
The infections occurred at a time when Britain was experiencing a jump in Covid-19 caused by a more contagious variant. A preliminary analysis found over half of the trial participants who became infected had the mutated version. The numbers are very small, but Novavax said they suggest the vaccine is nearly 96 percent effective against the older coronavirus and nearly 86 percent effective against the new variant. The findings are based on cases that occurred at least a week after the second dose.
Efficacy of the vaccine in the UK trial was close to that of the two authorised vaccines from Pfizer Inc with BioNTech and Moderna, whose two-dose regimens were both around 95 percent effective at preventing Covid-19 in clinical trials.
2B doses per year
Novavax shares surged 34 percent 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 authorisation with regulators.
The UK trial, which enrolled 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 meagre vaccine supply after Pfizer-BioNTech and AstraZeneca Plc delivered fewer doses than hoped.
Executives on the call said the company was discussing with the US Food and Drug Administration whether the UK and South Africa data was enough to apply for US emergency use authorisation.
60 percent efficacy acceptable
John Moore, a professor of microbiology and immunology at Weill Cornell Medical College in New York, said the Novavax UK data are essentially the same as results from Pfizer and Moderna.
"It's not statistically different. The vaccine basically works well in the predominant strain circulating in the UK, which means it's likely to be equally effective in the United States," he said.
Dr Amesh Adalja, an infectious disease expert at the Johns Hopkins Center for Health Security, said the results were in line with hopes, and that he was concerned people would focus too much on the weaker effectiveness shown in South Africa.
"We've gotten spoiled because we've seen the Moderna and Pfizer numbers. I know people are going to be alarmed, but 60 percent efficacy against the new variant is acceptable," he said, noting that the FDA initially said it would approve a vaccine that was at least 50 percent effective.
The South African variant has been shown to evade antibody protection in lab studies by Moderna and Pfizer/BioNTech.
Novavax said it started making new versions of its vaccine to protect against emerging virus variants in early January and expects to select ideal candidates for a booster in the coming days. The company said it plans to initiate clinical testing of these new vaccines in the second quarter of this year.
A 30,000-person trial in the United States and Mexico that began in December also is underway. The company has received $1.6 billion from the US government in funding for the vaccine trial and for 100 million doses.
It also has received at least $388 million in backing from the Coalition for Epidemic Preparedness Innovation (CEPI), a Norway-based group backed by 14 governments, the Bill and Melinda Gates Foundation, and Britain’s Wellcome Trust.
Authorised vaccines so far have been based on newer technology platforms, such as the messenger RNA technology used by Moderna and Pfizer/BioNTech, or inactivated cold virus platforms used by Oxford University/AstraZeneca and CanSino Biologics.
Novavax’s is a more conventional protein-based vaccine, an approach similar to that used by Sanofi to make its Flublok seasonal flu vaccine. The Novavax vaccine works with the company's proprietary Matrix-M adjuvant used to boost its efficacy.