And what that tells us about the pandemic.
What a vaccine's "efficacy rate" actually means.
French President Emmanuel Macron called on Thursday for the US and European nations to allocate up to 5% of current vaccine supplies to developing countries.
Why you might feel sick after getting a Covid-19 vaccine.
Why some Covid-19 vaccines were developed faster than any vaccine ever.
The European Union on Tuesday warned pharmaceutical giants that develop coronavirus vaccines to honor their contractual obligations after slow deliveries of shots from two companies hampered the bloc’s vaunted vaccine rollout in several nations.