Moderna is weighing a second booster shot to battle back a new coronavirus variant, even as it affirms its current vaccine's activity against newly emerging mutants.
While the current two-dose regimen is holding so far, it's less effective against a South African variant—which has the company exploring a third shot and a variant-specific booster.
The variant candidate is moving into preclinical studies and a phase 1 U.S. study, targeting the coronavirus strain first identified in South Africa, Moderna said Monday.
The South African variant, known as B.1.351, notched a sixfold reduction in neutralizing titers in tests made by Moderna and the National Institute of Allergy and Infectious Diseases (NIAID). Despite the decrease, the vaccine maintained levels expected to protect vaccine recipients, Moderna said.
Meanwhile, the vaccine appeared to deliver equivalent levels of neutralizing antibodies with the U.K. variant. The studies have been submitted as a preprint to bioRxiv with plans to submit for peer-reviewed publication.
Moderna CEO Stéphane Bancel said in the release that the company believes it’s “imperative to be proactive as the virus evolves” even as he reiterated confidence that the current Moderna shot will protect against new variants.
Both vaccine makers with emergency use authorization, Moderna and Pfizer, previously urged calm while they investigated their mRNA shots against the new coronavirus variants emerging around the world. Pfizer and partner BioNTech said in December that its testing showed its vaccine, Comirnaty, consistently “neutralized multiple mutant strains.” The partners are continuing to collect data on its activity against variants.