Novavax says Covid-19 vaccine is 89% effective in UK trial, but less so in South Africa

A vial of the Phase 3 Novavax coronavirus vaccine is seen ready for use in the trial at St. George's University hospital in London Wednesday, Oct. 7, 2020.

A new Covid-19 vaccine from Novavax was found to be 89% effective in a clinical trial conducted in the UK and appears to offer protection against some variants of the coronavirus, the American biotech firm has announced.

Novavax said Thursday that its vaccine was found to have been 95.6% effective against the original novel coronavirus, and 85.6% effective against the variant first identified in the UK, known as B.1.1.7, based on results from a Phase 3 trial conducted in the UK. The study included efficacy estimates by strain based on PCR tests performed on variants from 56 Covid-19 cases in the trial.

But the vaccine appeared to be less effective against a variant first identified in South Africa. The shot showed 60% efficacy among those without HIV in a separate Phase 2b study conducted in that country. The efficacy dropped to 49.4% when HIV-positive people were included.

Novavax said it was planning to start development of a vaccine specifically targeting the variant identified in South Africa. The company also said it had already started work on a new version of the vaccine that could be used as a booster shot against emerging strains. It aims to start clinical testing of this in the second quarter of this year.

The company's vaccine, known as NVX-CoV2373, "is the first vaccine to demonstrate not only high clinical efficacy against COVID-19 but also significant clinical efficacy against both the rapidly emerging UK and South Africa variants," Stanley Erck, Novavax president and CEO, said in the announcement. "NVX-CoV2373 has the potential to play an important role in solving this global public health crisis."

Regarding the trial in South Africa, "the 60% reduced risk against COVID-19 illness in vaccinated individuals in South Africans underscores the value of this vaccine to prevent illness from the highly worrisome variant currently circulating in South Africa, and which is spreading globally," Shabir Maddi, principal investigator in the Novavax Covid-19 vaccine trial in South Africa, said in the announcement.

"This is the first COVID-19 vaccine for which we now have objective evidence that it protects against the variant dominating in South Africa," Maddi said.

UK Prime Minister Boris Johnson welcomed the results of the British trial, hailing the "good news" that the vaccine candidate had proved effective and expressed his gratitude to "all the volunteers who made these results possible" in a tweet.

"Our medicines regulator will now assess the vaccine, which will be made in Teesside. If approved, we have 60m doses on order," he tweeted.

The UK's inoculation program has seen over 7.4 million people receive the first dose of a coronavirus vaccine so far, the latest government figures show. Two vaccines, from Pfizer/BioNTech and Oxford/AstraZeneca, are already in use in the phased nationwide rollout. The Moderna jab has received the green light too.

Novavax is also currently conducting a Phase 3 clinical study in the United States and Mexico and a Phase 1/2 continuation in the US and Australia, data from which are expected as soon as early first quarter 2021.

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