Moderna booster shots effective against Covid variants in early study

A single dose of Moderna’s original Covid-19 vaccine and a booster shot that targets key virus variants both show promising signals that they can protect previously vaccinated people against problematic strains, the company announced Wednesday.

The results from a preliminary study are an early sign that booster shots could play a role in future vaccination efforts — in this case, against the variants B.1.351, a strain first found in South Africa, and P.1, first found in Brazil, which are less susceptible to existing vaccines.

Moderna began a trial in March dosing vaccinate volunteers with a booster shot of its original formula or a modified vaccine aimed at B.1.351. The company and the National Institutes of Health also assessed the shots against P.1, a similar strain.

The study found that a booster dose of the variant-targeting formula was more effective than a booster of the original vaccine, but both raised antibody levels, Moderna said in a press release. The research is not yet peer-reviewed.

The boosters also appeared as safe as earlier shots, with volunteers reporting side effects similar to a second dose of the original Moderna vaccine.

There are several potential coronavirus boosters in lab and human studies as governments and pharmaceutical companies brace for possibly fading immunity in the face of spreading variants.

“As we seek to defeat the ongoing pandemic, we remain committed to being proactive as the virus evolves,” Moderna CEO Stéphane Bancel said in a statement. “We are encouraged by these new data, which reinforce our confidence that our booster strategy should be protective against these newly detected variants.”


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