Saudis will need to receive two COVID-19 vaccine doses to travel outside of the country beginning next month.

The Saudi Ministry of Interior announced on Monday that receiving the second dose of a coronavirus vaccine will be a condition for Saudi citizens to travel abroad beginning on Aug. 9, the official Saudi Press Agency reported. The decision was made based on Ministry of Health concerns about new variants of COVID-19 and the relative lack of effectiveness of receiving just a single dose, according to the agency. Many vaccines require two doses to be fully effective.

Saudi Arabia has required vaccination for travel and work in the recent past. In May, the government resumed allowing international travel for citizens who had been fully vaccinated or had received one dose two week prior to travel. On Aug. 9, the single dose will no longer be sufficient. Also in May, Riyadh announced that public and private sector workers would need to be vaccinated before returning to their places of work.

Around 41% of Saudis have received at least one vaccine dose, and roughly 12% have been fully vaccinated against COVID-19, according to the Oxford University-based Our World in Data.