Science‘s COVID-19 reporting is supported by the Pulitzer Center and the Heising-Simons Foundation.
The small biotech firm Novavax, once considered a dark horse in the COVID-19 vaccine race, announced today that its candidate delivered high efficacy—89.3%—in a pivotal trial in the United Kingdom where a new, highly transmissible variant of the pandemic coronavirus accounted for more than half of the cases in people in the trial.
“These are spectacular results,” Clive Dix, chair of the UK Vaccine Taskforce, said about the results from the trial, which enrolled more than 15,000 people. “This is an incredible achievement that will ensure we can protect individuals in the UK and the rest of the world from this virus.”
But the results from a Novavax trial that ran separately in South Africa, in which a new, troubling variant of SARS-CoV-2 accounted for many infections, were sobering. Among 4160 participants who were not living with HIV, the efficacy rate was 60.1%. It dropped to 49.4% when an additional 240 HIV-infected participants were included. The South African coronavirus variant has mutations that test-tube studies have suggested might allow it to escape antibodies roused by vaccines.
Laboratory studies on Moderna’s already authorized messenger vaccine recently found a degree of vaccine resistance to the variant, named B.1.351 (and sometimes referred to as 501Y.V2). But the Novavax results are the first hard evidence from human beings of the strain’s vaccine evasion. Says Moore: “Now we know that there is some loss in vaccine efficacy, down to around the 50% to 60% level. But that’s NOT zero. And a year ago we would have settled for a 50% to 60 % effective vaccine.”
In the U.K. trial, 62 cases of symptomatic COVID-19 occurred, 56 in the placebo group and six in vaccinees.
“The South Africa variant is a problem, and reducing its global spread is a priority. The more often it enters the USA, the more likely it is to expand, [for example] via a super spreader event,” says John Moore, a virologist at Weill Cornell Medicine.
As if to make that point, today the South Africa variant was first identified in the United States, in two people in South Carolina with no travel history, indicating that it may already be spreading in the community.
This is a developing story and will be updated.