Index: src/js/_enqueues/admin/site-health.js
===================================================================
--- src/js/_enqueues/admin/site-health.js	(revision 45048)
+++ src/js/_enqueues/admin/site-health.js	(working copy)
@@ -33,11 +33,14 @@
 		}
 	} );
 
-	$( '.health-check-accordion' ).on( 'keyup', '.health-check-accordion-trigger', function( e ) {
-		if ( '38' === e.keyCode.toString() ) {
+	// Arrows navigation on the accordion headers.
+	$( '.health-check-accordion' ).on( 'keydown', '.health-check-accordion-trigger', function( event ) {
+		if ( 38 === event.which ) {
+			event.preventDefault();
 			$( '.health-check-accordion-trigger', $( this ).closest( 'dt' ).prevAll( 'dt' ) ).focus();
-		} else if ( '40' === e.keyCode.toString() ) {
-			$( '.health-check-accordion-trigger', $( this ).closest( 'dt' ).nextAll( 'dt' ) ).focus();
+		} else if ( 40 === event.which ) {
+			event.preventDefault();
+			$( '.health-check-accordion-trigger', $( this ).closest( 'dt' ).nextAll( 'dt' ) ).first().focus();
 		}
 	} );