An experimental coronavirus vaccine developed by the biotechnology company Novavax is 89.3 percent effective in preventing Covid-19, the company announced on Thursday.
The results of the Novavax Phase 3 trial in the United Kingdom demonstrated the effectiveness of the candidate vaccine and showed that it protected against the United Kingdom virus variant. The results of another trial, in South Africa, showed that it was also effective against the variant that appeared there, although the effectiveness was less.
Stanley Erck, president and CEO of Novavax, based in Gaithersburg, Maryland, said the trial results show that the vaccine “has the potential to play an important role in solving this global public health crisis.”
Novavax, which received funding last year as part of the Trump administration’s Warp Speed operation, is conducting vaccine tests in the United States, the United Kingdom, Mexico and South Africa.
An interim analysis of the company’s UK trial, which included more than 15,000 participants aged 18 to 84, found that the vaccine was 95.6% effective against the virus and 85.6% effective against the most contagious variant of the UK.
The results were based on 62 infections among study participants, who received a two-dose vaccine or a placebo. Six of the infections observed occurred in the group that received the vaccine.
In the South Africa Phase 2 trial, however, the effectiveness was 49.4%. The study was conducted in a much smaller group of 4,400 people, many of whom were HIV-positive. In trial participants who were HIV-negative, the vaccine was 60 percent effective in preventing symptomatic Covid-19, Novavax said.
Novavax’s analysis was based on 44 infections among participants in the South African study, of which 15 cases were reported in the group that received the vaccine. Ninety percent of the Covid-19 cases analyzed at the trial were caused by the South African variant, the company said.
Moderna announced this week that its vaccine appears to be less effective against the South African variant, although it said the protective antibodies remained above protective levels. A Pfizer study, which has not been peer-reviewed, found that the Pfizer-BioNTech vaccine is only slightly less effective against the South African strain.
Unlike vaccines developed by Pfizer-BioNTech and Moderna, which use fragments of genetic code known as messenger RNA to trigger the immune system to produce protective antibodies, the Novavax vaccine relies on proteins synthesized from coronavirus to start the body’s immune system.
