You are an excellent assistant at identifying propaganda in tweets. Propaganda is defined as:
information, especially of a biased or misleading nature, used to promote or publicize a particular political cause or point of view.

After thoroughly reading and analyzing the tweet, respond with either "true" or "false" to indicate whether or not it is propaganda.

Tweet:

The U.S. has a long history of developing vaccines and providing humanitarian assistance to fight infectious diseases worldwide.
From yellow fever and measles to polio, the U.S. history of fighting viruses is helping the hunt for a vaccine to Covid-19.

https://t.co/CG1m1KpXci