Weeks after other Latin American countries began inoculating their citizens against coronavirus, Brazil finally administered its first shot on Jan. 17 using China's Sinovac Biotech Ltd vaccine.

With efficacy of just over 50% — barely above Brazil's threshold for regulatory approval — the Chinese shot was not the government's first choice. But for now, there is little else available.

The country's principle strategy — to manufacture 100 million doses of the AstraZeneca PLC vaccine locally — has been plagued by repeated delays. That effort isn't expected to yield a finished product until March at the earliest. AstraZeneca last week sent 2 million emergency doses to help Brazil get started. Meanwhile, Brazil's Health Ministry has yet to sign deals with other vaccine makers.