Now Playing: Trump on his plan to stop North Korea from testing nuclear weapons: ‘I’m not a dictator’ Now Playing…
The first major study to assess the safety and effectiveness of two different vaccines for the first time, using an…
Now Playing: Trump on his plan to stop North Korea from testing nuclear weapons: ‘I’m not a dictator’ Now Playing…
The first major study to assess the safety and effectiveness of two different vaccines for the first time, using an…