The number of people who made reservations for updated omicron-specific bivalent boosters reached almost 100,000, according to health authorities Friday.

The Korea Disease Control and Prevention Agency said it opened reservations on Thursday to anyone aged 18 or older. The number of people who made reservations as of 5 p.m. on Thursday reached 99,512, the agency added.

Previously, updated omicron-specific bivalent boosters were mainly available for people aged 60 or above. But the government decided to expand the vaccination amid an expected resurgence of infections in the winter.

Out of the reservations made so far, 66,264 people booked Moderna’s BA.1-targeting booster. 20,520 chose Pfizer's BA.4 and BA.5-specific bivalent booster. 11,459 chose the omicron BA.1-adapted bivalent vaccine. And 1,130 reserved the Novavax booster.

Inoculation of the omicron-specific boosters will start on Nov. 7, with an exception of Moderna’s BA.4 and BA.5-targeting booster. Vaccination of the Moderna booster and additional reservations for the booster will start on Nov. 14, according to the KDCA.

Moderna's BA.1-targeting booster, as well as the Novavax booster, will be available before Nov. 7, the KDCA added.

Experts said demand for BA.4 and BA.5-targeting booster is expected to increase later on as new COVID-19 strains are subvariants of omicron BA.5.

However, the KDCA noted it is currently uncertain which vaccine will be effective in order to minimize a possible resurgence of COVID-19 infections during winter.

The government also said the country will be able to secure enough BA.4 and BA.5-targeting boosters.

Korean health authorities encouarged people to receive their boosters, but antipicate the country’s COVID-19 booster rate may not increase much in the absence of enforcing vaccine pass rules.