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.
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.