The University of the Witwatersrand (Wits University) has clarified earlier statements about the apparent effectiveness of its experimental Covid-19 vaccine.

This comes after the university announced on Thursday 28 January that the Novavax Covid-19 vaccine trial in South Africa indicated it was effective against the new Covid-19 variant.

“The Novavax vaccine, known as NVX-CoV2373, is the first vaccine to demonstrate not only high clinical efficacy against the prototype SARS-CoV-2, but also significant clinical efficacy against both the rapidly emerging South African (501Y.V2 variant) and UK mutant (N501Y) variants,” the University said.

But media reports confused the efficacy trial percentage with an overall effectiveness. Wits has now clarified the initial comments saying the Novovax vaccine was 60% effective in combating HIV. It was, however, not as effective fighting the Covid-19 virus, slipping to 50% in trials.

When scientists combined the results for the two groups of test subjects,  the overall effectiveness of the jab went down to 49.4%.

Efficacy against the variant

The vaccine is being tested in both South Africa and the United Kingdom.

“The higher efficacy of the vaccine in the UK than in South Africa is because the variants circulating in SA are less sensitive to vaccine induced immune responses,” said Professor Shabir Madhi, head of the university’s Vaccines and Infectious Diseases Analytics research unit (VIDA).

“Nevertheless, 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,” he said.

“The public health value of vaccines extends beyond a simple point estimate. The ability of Covid-19 vaccines to impact the pandemic will depend on the product, its efficacy, and how quickly we can scale up coverage of the vaccine eventually,” Madhi explained.

Ongoing trials

In December, scientists discovered a new variant of the coronavirus, with lineages that may respond differently to existing vaccines. Wits said it plans to select ideal candidates for a booster and a possible combination bivalent vaccine to test against the new variant in the next few days.

As part of the second phase of trials, South Africa will enrol up to 2,904 volunteers between the ages of  18 and 64. The aim is to test the vaccine’s safety and effectiveness against the existing Covid-19 strain and the new variant.

The company plans to initiate clinical testing of these new vaccines in the second quarter of this year. But there are positive signs for production of the vaccine according to Novavax President of Research and Development, Gregory M Glenn.

“Combined with the safety profile that has been observed in our studies to-date with our Covid-19 vaccine, as well as prior studies in influenza, we are optimistic about our ability to rapidly adapt to evolving conditions,” he said.

The Novavax trial is part of the Coalition for Epidemic Preparedness Innovations (CEPI), which has funded manufacturing of doses and the cost of clinical trials. CEPI is supported in part by a $15 million grant from the Bill & Melinda Gates Foundation.—Health-e News