The US is currently donating doses to other countries in large quantities. Domestically, it has around 54m doses distributed but not used right now. (https://covid.cdc.gov/covid-data-tracker/#vaccinations). Some but certainly not all of those are at risk of expiration. If US authorities recommended booster shots for the general population then that would easily use up the currently unused supply and reduce vaccine exports.
The US is currently donating doses to other countries in large quantities. Domestically, it has around 54m doses distributed but not used right now. (https://covid.cdc.gov/covid-data-tracker/#vaccinations). Some but certainly not all of those are at risk of expiration. If US authorities recommended booster shots for the general population then that would easily use up the currently unused supply and reduce vaccine exports.