According to the CEO of Pfizer, a third shot may be needed within 12 months of the second dose.
Much like the Flu vaccine, the Pfizer COVID vaccine will be most likely be done annually to protect against the Coronavirus once you've done the first two shots.
While it hasn't been confirmed if this will be necessary, Pfizer and its German partner BioNTech are conducting studies to determine how long immunity from their vaccines lasts. Their findings from these studies will decide whether additional booster shots will be necessary.
The company behind the modern vaccine is working on a new vaccine that protects against new strains of COVID as well as the flu.