More than 21 million unused coronavirus vaccine doses have been discarded as of June in South Korea due to their expiration dates, data showed on Monday.

Among the 212.8 million vaccine doses that have been introduced into Korea, the discarded doses account for 10.86 percent of Korea's total contracted COVID-19 vaccine purchases, according to data released by the Korea Disease Control and Prevention Agency.

As the Korean government has not disclosed the per-shot purchase price of COVID-19 vaccines, it is impossible to calculate the value of the discarded doses accurately. The government signed confidentiality agreements with drug makers, so the actual purchase price per dose remains undisclosed.

However, the per-shot purchase price is known to have been 25,000 won ($19.40), according to local reports. Therefore, about 546 billion won is estimated to have been spent on vaccines that expired and had to be thrown away.

By year, 1.7 million doses of coronavirus vaccines were discarded in 2021, 10.7 million doses in 2022 and 10.9 million doses have been discarded through June of this year.

The expiration dates for coronavirus vaccines come sooner than those of other drugs. The Janssen vaccine is valid for six months, the Novavax is valid for 12 months and the Pfizer is valid for 18 months. Mass disposals are expected to continue as the expiration dates for the doses already in stock keep arriving.

Some critics have blamed the government for having purchased too many doses without being able to accurately predicting demand when the coronavirus vaccines were first introduced in Korea in 2021.

Although the KDCA emphasizes the need for everyone to be vaccinated, demand has plateaued or is declining as the number of people in the country who have been infected with COVID-19 has reached over half of the total population, and some people think that once they've been infected, they are immune forever, even though post-infection immunity to future infections varies greatly.

Also, people who are wary of side effects and choose not to get vaccinated altogether contribute to doses remaining unused and eventually getting wasted, according to the KDCA.

The KDCA told The Korea Herald that it is taking measures to extend the expiration dates of the country's stockpiled vaccines and is adjusting the timing of introducing further vaccines in consultation with pharmaceutical companies.

The KDCA has decided to introduce an updated version of the COVID-19 vaccine between October and November for this winter season, after finishing consultations with Moderna and Pfizer, the agency said.

“For unused vaccines, we work with related ministries, such as the Ministry of Foreign Affairs, to promote donating them overseas. In addition, domestic pharmaceutical companies can use the stockpiled vaccines to develop other vaccines, so we are considering providing them (to such companies),” the KDCA noted.

"It is also known that the United States and European countries secured sufficient numbers of vaccines and then disposed of them when they could not be used," the KDCA added.