HANOI, Vietnam (AP) — Vietnam on Wednesday started to vaccinate children as part of an effort to reopen schools after more than half a year of closures due to COVID-19.

About 1,500 teenagers between 16 and 17 years old in Ho Chi Minh City in southern Vietnam were among the first to receive jabs before the inoculation program is rolled out nationwide in November, the health ministry said on its website.

During the first phase, Vietnam has only approved the Pfizer vaccine for children. Parents or guardians must sign a consent form for their children to be vaccinated, the report said.

“Vaccination safety for children is the top priority,” health minister Nguyen Thanh Long said during a meeting on Tuesday ahead of the launch.

Last week, the ministry approved vaccinations for children between 12 and 17 years old, with older teens in more populated cities receiving priority for the first doses. There are about 14 million Vietnamese children in that age range.

According to the report, children will be vaccinated at their schools and those who do not attend school will be vaccinated at pediatric hospitals.

About 55% of Vietnam’s 98 million people have received COVID-19 vaccine jabs, but only half of them have been fully vaccinated with both doses.

Vietnam closed schools and education institutions in May when an outbreak fueled by the delta variant spread across the country. No date has been set for reopening schools, but the government is aiming for early 2022.

Southern provinces were the worst hit by the virus, with Ho Chi Minh City as the epicenter. About 800,000 people were infected and 20,000 died in less than four months as the outbreak surged.