China’s capital Beijing began offering booster shots for COVID-19 four months before the Winter Olympics.

State media reported that anyone 18 years or older who has received two-dose Chinese vaccinations and is a member of at-risk groups such as those organizing, participating in, or working on games facilities would be eligible for an additional shot.

Since late September, the booster has been in use in many cities throughout the country. However, Beijing authorities are more cautious about who gets the extra jab.

The games will begin on February 4, with only Chinese residents allowed to stand. Indoor events including jumping, sliding and skiing will be held in Yanqing and Zhangjiakou.

China has been successful in preventing local transmission by imposing strict requirements regarding mask wear, quarantining, and contact tracing. There are still cases, however. 28 new cases were reported Friday, one of which was in Fengtai, a Beijing suburb.

It is believed that the pandemic originated in Wuhan, a central Chinese city in late 2019. This lockdown affected over 50 million people.

China is accused of covering up the first coronavirus outbreak and stalling investigations into its origins. However, it stated earlier this week that it will cooperate with the World Health Organization’s renewed investigation while opposing all forms of political manipulation.

WHO released Wednesday a list of 25 experts that it will consult on the next steps in its search for the virus’ source after earlier attempts were attacked for being too soft on China.