He says Americans should be hopeful but not complacent.
Viruses mutate and evolve and the coronavirus is no different.
There's no evidence yet that vaccines "prevent people from actually getting the infection," official warns.
Adults over 75 are eight times more likely to be hospitalized after contracting the virus.
Italy and Austria are the latest countries to restrict flights from the U.K.
The pandemic has shipping companies performing a high-stakes juggling act.
The peer-reviewed findings help validate that the product works and is safe.