One dose of Covid-19 vaccines from AstraZeneca Plc and Pfizer was 86.6 percent effective in preventing infections among people aged 60 and older, real-world data released by South Korea showed on Wednesday.

Data by the Korea Disease Control and Prevention Agency (KDCA) showed the Pfizer vaccine, jointly developed by BioNTech, was 89.7 percent effective in preventing infection at least two weeks after a first dose was given, while the AstraZeneca shot was 86.0 percent effective...