Washington, Sep 2 (IANS): US drug maker Moderna has applied to the US Food and Drug Administration (FDA) for the evaluation of a booster dose of its mRNA-based Covid-19 vaccine.

Early trials have shown that the mRNA-1273 booster shot at 50 microgram dose level induced robust antibody responses of more than 40 times against the highly infectious Delta variant (B.1.617.2), the company said in a statement on Wednesday.

"We are pleased to initiate the submission process for our booster candidate at the 50 microgram dose with the FDA. Our submission is supported by data generated with the 50 microgram dose of our Covid-19 vaccine, which shows robust antibody responses against the Delta variant," said Stephane Bancel, Chief Executive Officer of Moderna, in the statement.

The Phase 2 study of mRNA-1273 was amended to offer a booster dose of mRNA-1273 at the 50 microgram dose level to interested participants six months following their second dose. Neutralising antibody titers had waned significantly prior to boosting at approximately six months.

A booster dose of mRNA-1273 at the 50 microgram dose level boosted neutralising titers significantly. After a third dose, a similar level of neutralising titers was achieved across age groups, notably in older adults (ages 65 and above).

The safety profile following dose 3 was similar to that observed previously for dose 2 of mRNA-1273. The data is yet to be submitted to a peer-reviewed publication.

An additional analysis showed that a booster dose of mRNA-1273 at the 50 microgram dose level induced robust antibody responses and significantly increased titers for all variants of concern including Beta (B.1.351) by 32- fold, Gamma (P.1) by 43.6-fold and Delta (B.1.617.2) by 42.3-fold, the company said.

Once approved, the company aims to submit data to the European Medicines Agency (EMA) and other regulatory authorities around the world.

The Moderna Covid-19 Vaccine is an mRNA vaccine against Covid-19 encoding for a prefusion stabilised form of the Spike (S) protein. The US FDA authorised the emergency use of the Moderna Covid-19 vaccine in individuals 18 years of age or older in December 2020.

It has received emergency authorisation for use of its Covid-19 vaccine in adults from health agencies in more than 50 countries.