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Novavax COVID-19 Vaccine Is 89 Percent Effective, But New Variants Remain A Problem


Tom Hale

Senior Journalist

clockJan 29 2021, 12:17 UTC

Novavax is a vaccine development company headquartered in Gaithersburg, Maryland. Image credit: rafapress/

Novavax's COVID-19 vaccine has been found to be 89.3 percent effective in a large-scale UK trial. 

Early results also suggest the vaccine is 85.6 percent effective against the UK variant of concern, which is promising, and approximately 60 percent effective against the fast-spreading South African variant, which is less promising. 


The findings have not yet been put under the scrutiny of a peer-review process, but the announcement is being widely considered as good news, with some scientists describing the findings as "exciting" and  "greatly reassuring." Others, however, have said the news is "mixed."

Novavax, a US biotech firm headquartered in Maryland, announced the findings of the Phase 3 clinical trial on Thursday, along with the results of a Phase 2b trial carried out in South Africa. 

The UK trial included 15,000 participants between 18 and 84 years of age – 27 percent of which were over the age of 65 – and concluded that the vaccine was 95.6 percent against the original COVID-19 strain and 85.6 percent against the UK variant strain, equalling an overall efficacy of 89.3 percent. 


In the South African arm of the trial, where over 92 percent of COVID-19 cases were the South African variant of the virus, the vaccine was 60 percent effective among the 94% of participants that did not have HIV.

Considering there has been much debate about whether the newly identified variants will respond to the vaccines, this is new information is being welcomed by scientists, although it has raised some concerns. 

“The finding that the Novavax vaccine gives high levels of protection in the UK limb of the trial is excellent,” commented Professor Peter Openshaw, Professor of Experimental Medicine at Imperial College London.


“The rather lower level of protection... seen in South Africa is a concern, given that the triple mutant variant virus (including three mutations in the receptor binding domain (RBD) and multiple mutations outside the RBD), was widely circulating at that time,” Openshaw added. 

"It is not unexpected news that the efficacy of the vaccine seems to be lower against the new UK variant," remarks Hassan Vally, an Associate Professor in Epidemiology at La Trobe University in Australia. "However, even taking into account this finding, the efficacy is impressive."

"The early results from South Africa are not as encouraging," adds Vally.


Novavax's vaccine, known as NVX-CoV2373, is a protein-based vaccine candidate engineered from the genetic sequence of SARS-CoV-2, the virus that causes COVID-19 disease. This effectively means it's a lab-made version of proteins found in SARS-CoV-2, which has been specifically tailored to create an immune response without causing the illness. The proteins are then loaded onto a nanoparticle carrier and injected into the body. This is notably different from RNA vaccines, such as Pfizer/BioNTech and Moderna, which work by tricking the body's own cells to manufacture the tiny parts of the virus.

Like some of these other COVID-19 vaccines, the Novavax vaccine requires two shots spaced three weeks apart. It also isn't a living vaccine and is stable at normal refrigeration temperatures, which is a positive. 

The UK government says they've secured 60 million doses of Novavax’s vaccine, scheduled to be delivered in the second half of 2021. Similar deals have been made with Canada for 52 million doses, and with Australia for 51 million doses. Next up, Novavax must submit their results to national regulators who will review the data and decide whether they want to approve the vaccine for use.

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