Some 760,000 South Koreans who have received a first dose of AstraZeneca Plc's Covid-19 vaccine will be offered Pfizer Inc's vaccine as a second shot due to shipment delays by global vaccine sharing scheme COVAX, the government said.

Several countries, including Canada and Spain, have already approved such dose-mixing mainly due to concerns about rare and potentially fatal blood clots linked to the AstraZeneca vaccine.

A Spanish study found that giving a dose of the Pfizer shot to people who already received the AstraZeneca vaccine is highly safe...