Two Covid-19 vaccines from China’s Sinopharm showed more than 70 percent efficacy against symptomatic cases, but it remains unclear how much protection they provide against severe or asymptomatic cases, according to the first detailed result of a large late-stage study published to the public.

China approved a Covid-19 vaccine developed by an affiliate of state-backed pharmaceutical giant Sinopharm on Dec. 31, the country’s first approved shot for general public use as it braces for increased transmission risks over winter.

Countries across the globe shut their borders to Britain on Dec. 21 due to fears about a highly infectious new coronavirus strain, causing travel chaos and raising the prospect of food shortages days before Britain is set to leave the European Union.

A coronavirus vaccine candidate developed by a unit of China National Pharmaceutical Group (Sinopharm) appeared to be safe and triggered antibody-based immune responses in early and mid-stage trials, researchers said.