Moderna is designing a new version of its COVID-19 shot to fight the variant first found in South Africa

Moderna is designing a new version of its COVID-19 shot to fight the variant first found in South Africa
Moderna's COVID-19 vaccine is one of two that have been authorized for emergency use to fight the pandemic across the US. The other vaccine available is from Pfizer.Radek Mica /AFP via Getty Images
  • Moderna says its current coronavirus shot probably protects against two fast-spreading variants.
  • But the shot showed lower levels of antibodies in lab testing against one of them.
  • The company is now tailoring a version of its vaccine to that strain, first found in South Africa.

Moderna's coronavirus vaccine is probably still protective against a virus strain first found in South Africa, but the Massachusetts biotech on Monday said it planned to soon start testing a booster shot tailored to protect people against that variant.

Moderna's two-dose COVID-19 vaccine won US authorization in December and has since been rolled out to millions of people. A large-scale study last year found the shot was overwhelmingly protective against COVID-19, being about 94% effective at preventing symptomatic disease.

Read more: More than 200 coronavirus vaccines are still in development as the initial vaccine rollout ramps up. Here's how experts anticipate 2021 playing out.

But infectious-disease experts have grown increasingly concerned with the recent rise of several variants, in particular one, known as B.1.351, that was first identified in South Africa. That version of the virus has 10 mutations in the spike protein, which is the target of the leading COVID-19 vaccines, including Moderna's.

New lab research from Moderna and its partner scientists at the US National Institutes of Health found the shot generated less of an immune response against that strain. That research hasn't been published yet in a medical journal, but Moderna said it believed the shot was still protective, at least in the short term.


Dr. Anthony Fauci, the top US infectious-disease expert, said Monday on NBC News' "Today" show that the current coronavirus vaccines were considered effective against existing strains.

Moderna is designing a new version of its COVID-19 shot to fight the variant first found in South Africa
Dr. Anthony Fauci is pictured above on November 19, 2020.Jabin Botsford/The Washington Post via Getty

"However, we really need to make sure that we begin, and we already have, to prepare, if it's necessary, to upgrade the vaccines," Fauci added.

Moderna's shot showed a sixfold reduction in neutralizing antibodies - the viral-killing proteins that play a critical role in the immune system - against the B.1.351 variant compared with other variants, the company said.

"These lower titers may suggest a potential risk of earlier waning of immunity to the new B.1.351 strains," Moderna said in a Monday press release.

Read more: Inside Moderna's historic coronavirus vaccine program that transformed the biotech upstart into a $55 billion drug industry powerhouse


Given the results, Moderna will soon start additional clinical trials. This research will test giving another booster shot of its current vaccine as well as a booster shot tailor-made to neutralize the B.1.351 variant.

Moderna CEO Stéphane Bancel said the biotech was starting the new program "out of an abundance of caution."

Moderna's vaccine did hold up well against a different fast-spreading variant, first detected in the UK, researchers found. Antibody responses against that strain were roughly in line with those against previous versions of the virus.

Regulatory pathway is unclear but likely to be significantly shorter

It's unclear when the human research would start, as Moderna said the variant-specific vaccine still needed to go through some preclinical testing.

Read more: Moderna's ambitions of pumping out up to 1 billion doses of a coronavirus vaccine rest on a former Polaroid factory that's never produced an approved drug


Experts say Moderna will need to run a new clinical trial of the booster shot before regulators will allow its use.

That, however, almost certainly won't require running another 30,000-person study that supported its December authorization in the US. Instead, a booster study is likely to be something closer to Moderna's 45-person early-stage trial that will test whether the new shot creates an immune-system response. Moderna started that study in March and released initial data by mid-May.

Bancel said he expected the booster trials "will follow a path similar to seasonal flu" vaccines, he told CNBC's Meg Tirrell on Monday.

For decades, flu vaccine developers have tweaked their products as new strains emerge. Drugmakers generally run a small immune-response test in humans and present that data, along with late-stage data that showed the previous version of the vaccine worked, to the Food and Drug Administration.

It's not a given, however. Bancel acknowledged the ultimate decision rested with the FDA. Many influenza vaccines use tried-and-true scientific approaches, while Moderna's and Pfizer-BioNTech's vaccines were the first messenger RNA products to hit the market in the US.


"There are decades of experience with influenza vaccines and the platforms used to develop and assess the efficacy of these products," David Morse, a former FDA pharmacologist who is vice president of global regulatory affairs at Icon, told Insider. "Whether the influenza procedures can safely be leveraged in the coronavirus milieu is as yet unknown."

The fact that so little is understood about the novel coronavirus, its variants, and what level of antibodies are needed to protect a person could also complicate the process, according to the Parexel vice president Bridget Heelan, who previously worked at Europe's regulatory agency.

Much more is known about influenza, she said, making COVID-19 a different scenario that will require people in the drug industry to learn as they go.