https://www.mercurynews.com/2022/01/07/fda-shortens-booster-timeline-for-moderna-covid-19-vaccine/

The FDA authorized Moderna’s booster shot to be given to adults five months after the initial two-dose vaccine series instead of six months, aligning with a change approved earlier this week for Pfizer’s vaccine.

“The country is in the middle of a wave of the highly contagious omicron variant, which spreads more rapidly than the original SARS-CoV-2 virus and other variants that have emerged,” said Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research.