GlaxoSmithKline Korea Ltd. said Wednesday that Korea’s drug agency has extended approval for its hot-selling pneumonia vaccine to be used in babies born premature at 27 to 28 weeks and children up to 5 years old.

The expanded approval makes Synflorix the first pneumococcal conjugate vaccine here for premature babies, the local unit of the U.K.-based corporation said.

The vaccine was first approved by the Korea Food & Drug Administration in 2010 for the prevention of invasive pneumococcal disease in infants and young children from 6 weeks through 2 years of age.

Pneumococcal disease, which can cause pneumonia, meningitis and sepsis, claims the lives of nearly 1 million children under 5 every year, more than 70 percent of which live in developing countries, GSK said.

Synflorix protects against 10 strains of the streptococcus pneumoniae bacterium, whereas its bigger rival ― Pfizer Inc.’s blockbuster drug Prevnar 13 ― prevents 13 strains.

GSK has been supplying the vaccine at $3.50 a shot to Africa and Latin America to help protect children there. The average price per shot in Korea is about 130,000 won ($115).

Global sales reached 221 million pounds ($348 million) in 2010, which is the latest available data.

The multinational pharmaceutical giant invested more than $400 million in launching a plant in Singapore in 2009 to meet surging demand for Synflorix.

“The KFDA’s decision underscores the growing significance of vaccines for pneumococcal infections, given a spike in both premature births and the number of babies who start group activities at foster care facilities at a very young age,” Margaret Rump, chief of GSK’s vaccine unit, was quoted as saying by the Seoul office.

More than 78 percent of Korean children aged five or younger use a childcare center, with 84 percent of them starting before 3 years old, according to the Korea Institute of Child Care and Education. The use of such facilities makes kids more vulnerable to infections.

The number of premature babies more than doubled to nearly 6 percent in 2010 from 1995, Statistics Korea reported.

“Pneumococcal vaccination is highly recommended for premature babies with less than 37 weeks of gestation to boost their immune systems,” said Kang Jin-han, a pediatrics professor at Seoul St. Mary’s Hospital of the Catholic University.

By Shin Hyon-hee (heeshin@heraldcorp.com)