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Moderna Developing COVID-19 Vaccine Booster Shot To Address Variants

Someone receiving a vaccine short in their arm.

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Key Takeaways

  • Moderna found that its vaccine may be less effective against the South African strain of SARS-CoV-2, the virus that causes COVID-19.
  • The company is creating a booster shot to target the variant.
  • Moderna is also studying a booster that could work with other vaccines, too.

Biotechnology company Moderna announced on Monday that it is working on a booster vaccine to protect against the South African variant of COVID-19, known as 501Y.V2. Moderna makes one of the two COVID-19 vaccines that have been authorized for use in the U.S.

Moderna said in a press release that it launched a clinical program to boost immunity to certain variants of SARS-CoV-2, the virus that causes COVID-19, “out of an abundance of caution.”

Moderna made the announcement after revealing the results of laboratory research on the blood of eight people who had been given their vaccine. That research found that the vaccine produced neutralizing titers—antibodies in the blood—that work against both the South African variant and U.K. variant, B.1.1.7.

But, while Moderna said that the study showed that B.1.1.7 had “no significant impact” on antibodies against the virus, there was a six-fold reduction in antibodies against 501Y.V2 compared to other variants. “These lower titers may suggest a potential risk of earlier waning of immunity,” the company said in the press release. But, despite the reduction, Moderna said that the antibodies “remain above levels that are expected to be protective.”

The study was conducted in collaboration with the Vaccine Research Center at the National Institute of Allergy and Infectious Diseases and has not yet been published or peer-reviewed.

“The two-dose regimen of the Moderna COVID-19 vaccine at the 100 µg dose is expected to be protective against emerging strains detected to date,” the press release says. “Nonetheless, Moderna today announced its clinical strategy to proactively address the pandemic as the virus continues to evolve.”

What This Means For You

Research has found that both COVID-19 vaccines authorized for use in the U.S. are effective against variants of the virus. When it's your turn, if you can, you should get vaccinated.

Next Steps for Moderna

The company announced that it will test an “additional booster dose” of its existing COVID-19 vaccine “to study the ability to further increase neutralizing titers against emerging strains beyond the existing primary vaccination series.”

Moderna is also working on a booster shot that would specifically work against the South African variant. Moderna said it is moving this booster shot into preclinical studies and a Phase 1 study to evaluate the benefit of creating a booster with “strain-specific spike proteins,” referencing COVID-19’s crown-like structure.

The company also said that it expects either one of its booster vaccines will be able to “further boost” antibodies when used with all of the leading vaccines and vaccines candidates, not just Moderna’s vaccine.

How the Current COVID-19 Vaccines Work

There are two COVID-19 vaccines currently authorized for use in the U.S.: the one made by Moderna and another from Pfizer-BioNTech. Both use a newer technology called messenger RNA (mRNA).

The mRNA vaccines work by encoding part of the spike protein that's found on the surface of SARS-CoV-2. The vaccines specifically contain pieces of the encoded protein from SARs-CoV-2 that your body mounts an immune response to. As a result, your body develops antibodies to the virus. Then, the protein and the mRNA are eliminated from your body, but the antibodies remain.

Pfizer announced in January that its vaccine is effective against COVID-19 variants.

What Experts Think

Doctors stress that reports about the COVID-19 vaccines and efficacy against new variants are good. “It’s reassuring that the Moderna vaccine appears to be effective against the U.K. strain,” Shobha Swaminathan, MD, associate professor and principal investigator for the Moderna Phase 3 trial at Rutgers New Jersey Medical School, tells Verywell. “For the South African strain, it wasn’t that the vaccine wasn’t effective—the titers were reduced. We just don’t know what that means yet clinically.”

John Sellick, DO, MS, an infectious disease expert and professor of medicine at the University at Buffalo/SUNY, tells Verywell that it’s important to remember that the news so far has been positive.

“It remains to be seen if and when we will need new vaccines or booster doses,” he says. “One of the good things that comes from this is the illustration of how these mRNA vaccines can be modified in a very short time frame as compared to traditional virus vaccines.”

David Cennimo, MD, an infectious disease expert and assistant professor of medicine at Rutgers New Jersey Medical School, tells Verywell that it’s “reassuring” that the vaccine-derived antibodies still bind well to variants of the virus to help prevent infection. But, he adds, “I suspect they do not bind as well as they would in a non-variant virus.”

Still, Sellick urges people to be patient. “Do not get exasperated as each press release comes out,” he says.

Swaminathan stresses that the booster shot is being created for a just-in-case scenario. “We don’t want to be blindsided,” she says. “But we don’t have information to suggest that it’s required.”

The vaccines have been found to be up to 95% effective at preventing future COVID-19 infection. “Even if the efficacy drops a little bit with a variant, it should still protect against severe disease,” she says. “The best way to curb the pandemic is to get as many people vaccinated as possible."

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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  1. Moderna. Moderna COVID-19 vaccine retains neutralizing activity against emerging variants first identified in the U.K. and the Republic of South Africa. Updated January 25, 2021.

  2. Centers for Disease Control and Prevention (CDC). Understanding mRNA COVID-19 vaccines. Updated December 18, 2020.