Moderna Inc has started a mid-stage study, testing a booster dose of its COVID-19 vaccine specifically designed to target the Omicron coronavirus variant, a day after rival Pfizer Inc (PFE.N) launched a similar trial.
The company said on Wednesday that while a third shot of its original coronavirus vaccine increased neutralising antibodies against the variant at the lower dose, their levels declined six months after the booster dose was administered.
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However, neutralising antibodies remained detectable in all participants, Moderna said.
While studies have indicated that Omicron results in a less severe COVID-19 than seen during previous waves, the variant has quickly become dominant in many parts of the world, driving up infections and straining healthcare systems.
Pfizer and its partner BioNTech started a clinical trial on Tuesday to test a new version of their vaccine specifically tailored to the Omicron variant.
Moderna said it would study its Omicron-specific booster in adults aged 18 years and older.
It promises to share its data from the trial with public health leaders so they can make evidence-based decisions on the best booster strategy against the coronavirus.
Three studies, led by the US Centers for Disease Control and Prevention have shown that a third dose of an mRNA vaccine, such as those from Pfizer and Moderna, is key to fighting the Omicron variant.
Some countries have already started offering additional booster doses, but a recent study from Israel showed that while a fourth dose of an mRNA vaccine boosted antibodies, the level was not high enough to prevent an Omicron infection.