Emily Scarratt, Katy McLean, Amy Wilson-Hardy and Amy Cockayne all also claimed scores, with a penalty try rounding off another rout as Simon Middleton's side topped Pool B.

The USA scrambled a try bonus point in defeat however, thanks to scores from Kate Zackary, Cheta Emba, Naya Tapper and Kristen Thomas.

But England were not to be denied safe passage to the last four with a powerful win in Dublin, Middleton's side joining New Zealand in reaching the semi-finals.

Scarratt kicked off England's comfortable win, reaching McLean's neat grubber first to dot down.

The 2014 world champions then flexed their tight-game muscles with a fine rolling lineout maul, that was brought down illegally by the USA's Katy Augustyn.

Augustyn was sin-binned and England awarded a penalty try, handing Middleton's side early control.

England profited from another driven maul when Packer rose last from the pile of bodies to claim her side's third score.

And when England and Packer capped another driven maul with their fourth score, the game looked over as a contest as early as the 26th minute, with England leading 28-0.

Flanker Zackary hit back for the USA though, with the converted try handing the Americans a foothold on the scoreboard.

McLean restored the England supremacy with their fifth try however, to leave Middleton's side coasting at 33-7 to the good at the break.

Wilson-Hardy capped a flowing move for the sixth score straight after the restart, before Cockayne finished the seventh try after just 48 minutes.

The USA refused to go quietly however, with full-back Emba sneaking home for a score, before England sent on a raft of replacements.

Tapper took advantage of the disarray to step through traffic for a smart score for the USA, before Thomas claimed the bonus point try on the stroke of full-time.