South Korea has commenced this year’s flu vaccination program ahead of the winter season that offers free injections for young children and the elderly on Wednesday, according to the quarantine authorities.

The Korea Disease Control and Prevention Agency said that the vaccination program will run through April 30 next year, stressing that the vaccination would dramatically reduce the chance of catching the flu.

The target groups for this program are children aged six months to under 13 years, pregnant women, and those aged 65 and older.

The program opens first for children aged between six months and nine years who haven't had flu shots before. They are required to receive two doses of the flu vaccine with a four-week interval between them.

Other children and expecting mothers who have received an influenza vaccine in the past can get free flu shots starting Oct. 5.

Also, those aged 75 and above can receive the vaccine starting from Oct. 11, individuals aged between 70 and 74 from Oct. 16, and those between 65 and 69 from Oct. 19.

A total of 27.3 million doses of flu vaccine is set to be distributed nationwide. Those not eligible for this free national vaccination program can receive their flu shots at local medical institutions for a fee. The fee varies depending on the medical institution, but it usually ranges from 20,000 won ($15) to 40,000 won.

Flu vaccination is strongly recommended, according to the KDCA. “The flu vaccine is generally considered to be 70-90 percent effective in preventing the illness. It takes about two weeks after vaccination for a person to develop protection against the flu,” an official from the KDCA said.

All flu vaccines used in Korea are currently "quadrivalent," as recommended by the World Health Organization, which protect against four strains of the flu, according to the KDCA.