Moderna exploring potential need for COVID-19 booster shots

Moderna is developing a booster shot to its COVID-19 vaccine that aims to improve its protection against the coronavirus variant first identified in South Africa. 

The company said Monday that its vaccine is effective against the South African variant and the variant first discovered in the United Kingdom. But it produces a weaker response against the South African variant.

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Moderna's two-shot vaccine had a sixfold reduction in neutralizing antibodies — which fight the virus — against the South African variant, according to a study the company conducted with the National Institute of Allergy and Infectious Diseases. But the vaccine still produced enough antibodies to be effective against the virus. 

The vaccine held up against the U.K. variant, producing the same amount of neutralizing antibodies as it did against prior forms of the coronavirus. The study, which tested blood samples from eight people who received two doses of the vaccine and two monkeys, has not yet been peer-reviewed. 

Moderna is launching two clinical trials to test whether a booster shot can improve the vaccine's response to the South African variant. One study will test whether administering a third shot of the existing vaccine is more successful at neutralizing the variant. The other study will test a third shot that specifically targets the variant. 

The studies are being launched as a proactive measure, Moderna officials said, emphasizing its vaccine still produces a protective response against both variants. The company does not yet have data on the vaccine's response to a variant found in Brazil.

"We’re doing it today to be ahead of the curve should we need to," the company's Chief Medical Officer Dr. Tal Zaks told the New York Times. "I think of it as an insurance policy. I don’t know if we need it, and I hope we don’t."

Dr. Paul Offit, director of the Vaccine Education Center at the Children's Hospital of Philadelphia, told CNBC that he's pleased Moderna is taking a proactive approach against the possibility of resistant variants. 

"This is not a problem yet," Offit said. "Prepare for it. Sequence these viruses. Get ready just in case a variant emerges, which is resistant." 

The South African and Brazilian variants have not yet been detected in the United States. Cases of the U.K. variant have been detected in numerous states, including Pennsylvania and New Jersey.

Medical experts are concerned about the South African variant because research suggests it is highly transmissible, but there isn't yet "clear evidence of the new variant being associated with more severe disease," according to the World Health Organization. 

There is some data suggesting the U.K. variant may carry a higher risk of death for infected people, but a top U.K. science official said "the evidence is not yet strong." Officials are awaiting the results of research underway. 

Last week, Pfizer released data showing its vaccine protects against the U.K. variant. 

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