Moderna Inc on Tuesday sought U.S. authorization for its COVID-19 booster shot tailored against the BA.4 and BA.5 subvariants of omicron and said if cleared it would be ready to deliver the doses in September.

Its application with the U.S. Food and Drug Administration (FDA) is based on pre-clinical data for the so-called bivalent dose that contains the dominant BA.4/BA.5 variants along with the original coronavirus strain.

Moderna said a mid-to-late stage trial for the vaccine is under way.

The submission also includes clinical trial data for its BA.1 omicron-targeting bivalent booster candidate, which was last week cleared in Britain.

Moderna's announcement comes a day after rival Pfizer Inc and German partner BioNTech sought U.S. authorization for their vaccine booster retooled to target the BA.4/BA.5 subvariants of omicron.

Pfizer's application is for emergency use among 12 years and older, while Moderna has sought authorization for use among people aged 18 and above.

Pfizer said the doses would be ready to be shipped immediately after the regulatory clearance. Moderna too has been ramping up the production of the BA.4 and BA.5 targeting vaccine to be ready for delivery next month.

Countries including the United States, Britain, and EU members have been preparing for vaccination campaigns in the fall season to protect against future surges.

The FDA had in June asked vaccine makers to tailor shots to target the two dominant subvariants and said it would not require studies testing the shots in humans for authorization, similar to how annual changes to flu vaccines are handled.

In human and pre-clinical trials, Moderna's two booster shots against the BA.1 as well as BA.4 and BA.5 subvariants showed strong neutralizing activity compared to the booster against the original coronavirus strain, the company said.

• Pfizer Asks FDA to Authorize Omicron Vaccine