Sarah Beckett’s red card meant that the Red Roses played with 14 players for most of the game, but they still triumphed 48-0 in Parma.
Italy never approached their tryline, even though the visitors led 10-0 after a first half riddled with errors.
After earning her 100th cap, Packer told News Sport, “[I am] on top of the world if I am being honest with you.”
“As a team, we expressed our desire to remove the handbrake, but some careless plays were made.
“It is the first game of the tournament; we will fix up and come back stronger against Wales.”
Coach John Mitchell’s team turned things around after a lackluster first half, scoring six tries in the second half to easily defeat a team they had defeated by 50 points or more in their previous five games.
Against Sweden in 2008, Packer made her Red Roses debut and became the seventh Englishwoman to attain 100 caps.
The 34-year-old was voted World Rugby Women’s Player of the Year for 2023 after defeating the Black Ferns to win the inaugural title, which came after winning her 99th cap last November.
“I would like to express my gratitude to my friends and family for making this trip so memorable for me,” stated Packer, who succeeded Sarah Hunter as England captain the previous year.