North Korea tested 674 people for COVID-19 around the last week of July and found no positive cases, the country told the World Health Organization (WHO), as a U.N. agency reported that it is working with the country to prepare supply chains for future vaccine distribution.

The DPRK tested 99 people with flu-like illness or acute respiratory infections and 575 health care workers from July 23-29, the WHO said in its weekly situation report released Monday.