``I've had a scratchy throat for a couple of days, but am feeling fine otherwise,'' Obama said on Twitter. ``Michelle and I are grateful to be vaccinated and boosted.''

Obama encouraged more Americans to get vaccinated against the coronavirus, despite the declining infection rate in the US.

There were roughly 35,000 infections on average over the past week, down sharply from mid-January when that average was closer to 800,000.

The Centers for Disease Control and Prevention report that 75.2% of US adults are fully vaccinated and 47.7% of the fully vaccinated have received a booster shot.

The CDC relaxed its guidelines for indoor masking in late February, taking a more holistic approach that meant the vast majority of Americans live in areas without the recommendation for indoor masking in public.