The health ministry gave fast-track approval to the use of U.S. drugmaker Moderna Inc.’s COVID-19 vaccine doses as booster shots on Thursday, as Japan hopes to speed up the rollout of third doses amid worries over the highly transmissible omicron variant.

The move, which came a day after approval by a ministry panel, marked the second such approval after that for the Pfizer Inc.-BioNTech jab.

Japan began administering booster shots on Dec. 1, starting with health care workers. Moderna’s shot is set to be allocated to a workplace vaccination program starting around March. Studies have shown that, unlike Pfizer’s vaccine, a Moderna booster containing only half the dosage of each of the first two shots is needed to beef up immunity. It is also expected to have a low rate of side effects such as myocarditis, according to the U.K. Health Security Agency.