Moderna’s experimental booster shot protects against variants first discovered in SA and Brazil

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  • Moderna's new booster shot has been found to work against the virus variants first identified in SA and Brazil
  • The company announced the results of a small-scale study this week
  • These promising data were submitted to a pre-print server and must still be peer-reviewed

Moderna has tested its first Covid booster shot, and according to preliminary results, it may "neutralise" the virus variants first identified in South Africa (B.1.351/501Y.V2) and Brazil (P.1/501Y.V3).

The US biotech company announced the findings from its Phase 2 study on Wednesday, saying that they are “encouraged by these new data”.

The firm started developing these variant-specific boosters in January 2021 after evidence showed that the newer variants could escape vaccine-induced immunity.

The booster shot was given to volunteers six to eight months after their first round of shots. Both the Moderna and the Pfizer vaccines, which use mRNA technology, require two shots.

 “Our mRNA platform allows for rapid design of vaccine candidates that incorporate key virus mutations, potentially allowing for faster development of future alternative variant-matched vaccines should they be needed,” said Moderna CEO Stéphane Bancel.

What the study involved

In the small clinical trial, the new booster was tested on the 40 volunteers who'd already been fully vaccinated with the two doses. They were then tested for their levels of neutralising antibodies, which are proteins responsible for defending cells from pathogens, such as SARS-CoV-2.

At the beginning of the study, only about half of the volunteers had detectable levels of antibodies against 501Y.V2 and 501Y.V3.

They were then given one of the following: 

  • Another dose of the existing formula/original Moderna vaccine
  • A version tailored specifically to the 501Y.V1 variant 
  • A version that combined a 50/50 mix of the two

Two weeks later, the researchers tested the group’s antibody levels again. Among the participants who received the original Moderna vaccine or the booster against 501Y.V2, the results showed both groups had improved antibodies against both the 501Y.V2 and 501Y.V3 variants. They said data on the 50/50 mix group are expected shortly. 

But, the promising news is that those given the new booster were found to produce even higher variant-specific neutralising antibodies compared to participants who received the original shot.

The results have been submitted to pre-print server bioRxiv, and have yet to be peer-reviewed.

Speaking to Bloomberg, Bancel said that the results are significant, “because every version of products that we can advance and show efficacy and safety in, is ultimately tied to saving lives”.

He added: “As the virus changes its tactics … through mutations … so should our vaccines respond a step ahead and boost our immune system’s ability to tackle the threat(s).”

Variants have spread 

By mid-April 2021, the worrisome 501Y.V2 variant was detected in at least 60 other countries, the Wall Street Journal reported. 

The fast-spreading variant is currently dominating Covid infections in South Africa and was responsible for more than 90% of infections in the second wave. However, there is no evidence that this variant causes more serious illness than the original variant.

The 501Y.V3 variant has been detected in at least 20 other countries, according to the WSJ. It is also highly transmissible and is partly responsible for the high death toll in Brazil.

Will other vaccines offer protection?

Apart from Moderna’s new booster shot, two new real-world studies published this week revealed that the Pfizer jab is highly effective at protecting against severe outcomes – including severe pneumonia and death – caused by 501Y.V2 and 501Y.V1 (first identified in the UK).

One study, published in the New England Journal of Medicine, indicates that the vaccine was administered to more than 200 000 people in Qatar where both 501Y.V1 and 501Y.V2 are circulating.

Updated Novavax results

Meanwhile, on Thursday, the University of the Witwatersrand (Wits) announced additional results of the Novavax Covid-19 vaccine trial. According to the report on the phase 2b study conducted in South Africa, the jab protects against mild Covid infection caused by the 501Y.V2 variant circulating in South Africa, while an updated analysis indicated 100% protection against severe disease caused by this variant.  

“The data make a compelling case for use of the Novavax Covid-19 vaccine in settings where the B.1.351 (501Y.V2) variant dominates – which is most of southern Africa – to reduce the risk of mild disease and also to maximise the opportunity for protection against severe Covid,” said Shabir Madhi, Professor of Vaccinology, who led the trial in South Africa.

In February, Madhi told The Conversation that the vaccine was only likely to become available in April or May 2021. He added that the government needed to engage with relevant stakeholders to secure supplies.

SA receives Pfizer vaccine

The first batch of Pfizer’s vaccines – 325 260 doses – landed at OR Tambo International Airport on Sunday evening, News24 reported. South Africa is set to receive a total of 30 million doses – enough to vaccinate 15 million people.  

Earlier this year, the government said they were in discussions with several pharmaceutical companies, including Moderna, about the procurement of vaccines. However, there has not yet been any indication that the country will receive either the Moderna or the Novavax jabs.

*For more Covid-19 research, science and news, click here. You can also sign up for our Daily Dose newsletter here.

READ | Why South Africa stopped making vaccines

READ | Risk of blood clots due to Covid-19 much higher compared to risk associated with vaccine - experts

READ | EXPLAINER: How we know vaccines are safe and effective

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