JAKARTA, Jan. 14 (Xinhua) — Indonesia launched its massive COVID-19 vaccination program on Thursday with health workers as the main priority group, a day after President Joko Widodo received the first shot developed by China’s biopharmaceutical company Sinovac Biotech.

On Thursday morning, a mass vaccination was held at state-run Cipto Mangunkusumo Hospital in central Jakarta.

At least 25 health workers at the hospital have received doses of the Sinovac vaccines, Lies Dina Liastuti, the hospital’s director, told a press conference, adding that about 6,000 health workers nursing patients at the hospital are to be vaccinated periodically.

“Thanks to the government for providing protection to health workers by providing the COVID-19 vaccines,” Liastuti said.

Deputy Minister of Health Dante Saksono, who received a dose of the vaccine at the hospital on Thursday, said more than 1 million health workers across the country will be vaccinated gradually before public servants get inoculated.

Immunity would appear between two and six weeks after the injection of the second dose of the vaccine. But those who have been vaccinated still need to implement health protocols, Saksono said.

The deputy minister expressed hope that the massive vaccination program would help Indonesia reach herd immunity after 181.5 million people — around two thirds of the country’s population — are inoculated in a period of 15 months.

The country’s food and drug authority BPOM issued an emergency use authorization for Sinovac’s COVID-19 vaccine on Monday after interim results of its late-stage trials in the country showed an efficacy rate of 65.3 percent.

The vaccine has also been declared halal by the Indonesian Ulema Council, or acceptable for use under Islamic law.

After receiving the shot on Wednesday, Widodo said he did not feel any pain from the injection. “It doesn’t hurt at all,” said the president with a laugh.

“We need to do the vaccination to stop the chain spread of COVID-19 and give health protection to us and the safety to all Indonesian people. It will also help accelerate economic improvement,” he added.

Following the president, the Indonesian military chief, national police chief and health minister, among others, were also vaccinated on Wednesday.