Vaccine distribution will begin when the FDA issues Emergency Use Authorization (EUA) for the vaccines.
Because of limited supply, vaccine doses will be distributed to certain segments of the population in a phased approach. The first phase will include the highest-risk populations, like health care workers, first responders and seniors in care settings. Additional segments of the population will be added as the supply increases. Once there is sufficient supply, anyone who wants a vaccine will be able to get one.
Note that some vaccines may require two doses spaced apart in order to be effective. When vaccines are available, members should work closely with their health care providers to determine if and when they should get the vaccine.
You can also find answers to many of your vaccine questions through the CDC.