US drugmaker Merck & Co Inc has begun recruiting participants to its early-stage Covid-19 vaccine study, according to the government database clinicaltrials.gov.

The study is based in Belgium and aims to recruit 260 participants. The WSJ first reported the news.

Earlier this month, Chief Executive Officer Kenneth Frazier had said the company aims to start human trials on one of its Covid-19 vaccine candidates “fairly soon,” with a second vaccine candidate likely to begin trials later this year.