SEOUL -- South Korea said 18,489 people received their first doses of AstraZeneca PLC’s vaccine by midnight on Friday as it launched an ambitious COVID-19 inoculation campaign, and will begin using Pfizer/BioNTech vaccines on Saturday.

The first to receive the shots are healthcare workers, staffers at assisted care facilities and other high-risk people, with a goal of vaccinating 32 million to 36 million people - some 60 percent to 70 percent of the population - by September.

The government hopes to reach herd immunity, defined as at least a 70 percent vaccine take-up, by November, as health authorities remain on alert for signs of sporadic infections.

The first AstraZeneca vaccines are to be administered to 289,000 people, while about 55,000 healthcare workers in coronavirus treatment facilities will receive first batch of the vaccine developed by Pfizer Inc and BioNTech SE supplied through the COVAX global vaccine-sharing programme.

Aside from AstraZeneca, Pfizer and COVAX, South Korea has also reached agreements with Moderna Inc, Novavax Inc and Johnson & Johnson for vaccines.

South Korea reported 415 infections of the new coronavirus for Friday.

The country has recorded 89,321 infections and 1,595 COVID-19 deaths, the Korea Disease Control and Prevention Agency said.

The authorities are extending social distancing rules by two weeks nationwide, including a ban on private gatherings of more than four, to blunt the coronavirus surge, Prime Minister Chung Sye-kyun on Friday.