Report: U.S. To Export Vaccines To Mexico, Canada

The U.S. is reportedly getting ready to ship out millions of vaccine doses to our neighbors to the north and south.
According to an Associated Press report, 4 million doses of the AstraZeneca vaccine will be exported – 2.5 million to Mexico and 1.5 million to Canada.
The U.S. has not yet approved AstraZeneca’s vaccine for emergency use, but tens of million doses are stockpiled for when that authorization is granted.
The shipment is being described as a “loan” for the two countries.
Should the U.S. be sending vaccines to other countries before all U.S. citizens are vaccinated? Why do you think the AstraZeneca vaccine hasn’t been approved yet when three others have been?