Earlier this week, the United Kingdom (U.K.) became the first country to approve Moderna's reformulated version of its COVID-19 vaccine, which claims to provide protection against both the original form of the virus and the significantly less lethal but more transmissible Omicron variant.

The product was approved by the U.K.'s Medicines and Healthcare Products Regulatory Agency (MHRA) with the support of the U.K. government's Commission on Human Medicines.

Described by U.K. officials as a "sharpened tool" in the nation's continued vaccination campaign, the reformulated vaccine combines the previously approved COVID-19 vaccine with a "vaccine candidate" targeting the Omicron variant BA.1.

That vaccine candidate has never been previously approved and has not been the subject of independent study. The MHRA approved the vaccine based on a single, incomplete human trial currently being conducted by Moderna.