Moon said Monday at a meeting of presidential Blue House aides that he would "devote himself" to "vaccine cooperation" with the United States in his upcoming summit with U.S. President Joe Biden, the Dong-A Ilbo reported.
South Korea in January confirmed that it had secured enough vaccines for 76 million people. The country had secured doses from AstraZeneca to cover 10 million people and enough doses from Janssen to inoculate 6 million.
Rare blood clots have been associated with vaccines from both companies, however.
Moon's statement comes after Japanese Prime Minister Yoshihide Suga requested U.S. drug manufacturer Pfizer Inc. for more COVID-19 vaccine after his first summit with Biden. Japan has been slow to roll out vaccines ahead of the scheduled 2021 Tokyo Summer Olympics.
Seoul has not provided an official explanation for the slow introduction of vaccines. Only 0.1% of South Koreans are fully vaccinated, and 2.9% of the population have received one dose. Meanwhile, the country has reported more than 600 cases daily in April, and total cases since the start of the pandemic stand at more than 115,000.
The results could be affecting Moon's standing in the polls.
A poll commissioned by local network YTN and conducted by Realmeter from April 11 to 16 showed Moon's approval rating remained in the 30% range at 34.7%.
The majority of South Korean respondents who disapproved of Moon's governance said the president and his administration have been "wrong" or "very wrong" in their policies.
The poll also showed support for the main opposition People Power Party remained higher than the ruling Minjoo or Democratic Party since the election of opposition politicians to mayors' offices in Seoul and Busan.
Moon's administration is coming under criticism for lack of transparency on vaccine safety.
The president publicly took the AstraZeneca vaccine in March to dispel concerns, but the government is being charged with not sharing cases of patients who experienced side effects, the Korea Herald reported Monday.
Seoul's parliamentary and welfare committee said Sunday that a nursing assistant spent weeks battling a fever and limb paralysis, but officials did not disclose the case, according to the report.