South Korea has walked back its plans to ease restrictions in the capital region for people who have been vaccinated against COVID-19, as the country struggles with another virus resurgence despite continued vaccination efforts.

Face masks will again be mandatory and drinking outdoors past 10 p.m. will be prohibited in the Greater Seoul area, even for those vaccinated against COVID-19. These rules are to be enforced indefinitely until the authorities decide that the COVID-19 situation has improved.

Korea’s disease control authorities said Sunday that the government had decided to strengthen virus control measures in Seoul, Incheon and Gyeonggi Province, effective immediately, as the number of cases remained high in those regions.

The country reported 711 new COVID-19 cases throughout Sunday, 644 locally transmitted and 67 imported from overseas, raising the cumulative total to 160,795, according to the Korea Disease Control and Prevention Agency.

Seoul, Incheon and Gyeonggi Province accounted for more than 80 percent of the new cases reported during the past 10 weeks. More than half involved people in their 20s or 30s.

With the continued surge in cases in the Greater Seoul area, the government decided to rethink some of the incentive programs it had planned to promote COVID-19 vaccination. Authorities said this was done to control the number of new cases.

The health authorities have emphasized that it is imperative to control infections now, considering the fast spread of the delta variant, which was first identified in India.

Close to 30 percent of Korea’s population has received first shots for COVID-19 and 10.4 percent of the population is fully vaccinated, but the virus situation remains serious. It has been reported that some of the available vaccines are not as effective against the delta variant.

The Central Disaster and Safety Countermeasures Headquarters said face masks will continue to be required in all indoor and outdoor public places, contrary to its original statement that vaccinated people would be allowed to take off their masks in parks or other outdoor recreational areas.

Violators will face fines of up to 100,000 won ($88), and operators of public facilities will face fines of up to 3 million won if they fail to enforce the rules.

To curb the spread of the virus at private gatherings, the government said it will ban outdoor drinking at public urban and riverside parks after 10 p.m., when restaurants and bars close in line with social distancing rules. People have been gathering outdoors to drink after restaurants and bars close.

Exactly when these rules take effect in each city or province will differ depending on how fast actual administrative orders are officially imposed. But there is no end date, and whether to lift them will be under the discretion of virus control authorities.

The government said it would enforce the rules strictly. Authorities are planning to conduct more inspections of public facilities to ensure that the rules are closely followed.

Korea was planning to ease its distancing rules this month but delayed the changes for one week, until Wednesday, due to a recent resurgence of COVID-19. Under the new rules, the ban on private gatherings of five or more people and the 10 p.m. curfew on businesses were to be lifted.

The disease control agency added that its virus testing centers in Seoul, Incheon and Gyeonggi Province would operate for longer hours to accommodate the demand for more testing.