However, the two doses still offered protection against serious illness, hospitalization and death.
The companies said they wanted to wait for data on a three-dose vaccine course that may offer stronger protection.
A second booster can be given four months after the first booster.
Please note, if you receive the Moderna booster, you will receive half of the original Moderna dose.
Nothing in this website is meant to be used for medical or nursing diagnosis or professional treatment.
Please be sure to confirm this with the person giving you the shot.