The vaccination campaign in the global financial hub has lagged many other developed economies, with about 65% of the eligible population fully vaccinated with shots from either China's Sinovac, or Germany's BioNTech.
About 85% of those older than 80 in the Chinese-ruled city of 7.5 million have not been vaccinated.
The elderly will get priority for the booster shots, along with health workers, cross-border truck drivers and others in categories deemed to be at higher risk of getting the disease.
About 1.86 million people are eligible for the booster, which they can start booking from Nov. 5, to receive it as soon as Nov. 11.
"The elderly are the most fragile group and we have a responsibility to protect their health," Chan said.
Hong Kong is following Beijing's lead in retaining strict travel curbs, in contrast to a global trend of opening up and living with the coronavirus.
International business lobby groups have warned Hong Kong could lose talent and investment, as well as competitive ground to rival finance hubs such as Singapore, unless it relaxes its restrictions on travel.
Despite barely any recent local cases and an environment virtually free of COVID-19, Hong Kong has imposed mandatory hotel quarantine of up to 21 days for arrivals from most countries at the travellers' cost.
Those who test positive are immediately admitted to hospital regardless of their condition. Since last month they have been required to spend a further 14 days in a designated facility after leaving the hospital.
(Reporting by Donny Kwok; Editing by Clarence Fernandez)