A senior Chinese epidemiologist said the United States should be the priority in the next phase of investigations into the origin of Covid-19 after a study showed the disease could have been circulating there as early as December 2019, state media said on June 17.

Leaked documents from provincial and municipal governments in China reveal a slew of previously unreported severe adverse events related to Covid-19 vaccines made and administered in China.

Sinovac Biotech’s annual production capacity of Covid-19 vaccine can reach 2 billion doses by June, a company spokesman confirmed to Reuters on March 3.