The Seoul Metropolitan Government is urging local elderly residents and those with underlying conditions to get COVID-19 vaccine booster shots.

Disease control officer Park Yoo-mi made the request in a press briefing Tuesday, while pointing out that nearly half of recent transmissions in the capital were breakthrough infections.

Such cases involve people who contract the coronavirus after being fully vaccinated or between their first and second shots.

Park said of the 646 new coronavirus cases that were confirmed Sunday, 49.4 percent invovled people who received a full regimen of COVID vaccines.

She stressed the rate of those cases is higher in Seoul than the national average.

Additional doses are currently available for people aged 75 and up as well as workers and patients at senior care centers.