China's capital Beijing has begun offering booster shots against COVID-19, four months before the city and surrounding regions are to host the Winter Olympics.

State media reported those older than 18 who have received two-dose Chinese vaccines and belong to at-risk groups, including those organizing or working on games facilities, would be eligible.

The booster has been rolling out nationally since late September, but Beijing authorities have been extra cautious in who receives the extra jab.

China has been largely successful in preventing local transmission through strict requirements on mask wearing, quarantining and contact tracing.

Cases continue to pop up, however, with 28 new ones reported Friday.