Do I need a HEPA-sealed vacuum if I have pets and allergies?

If anyone in the home has pet dander allergies, reviewers consistently recommend a true sealed HEPA system rather than just a HEPA-rated filter. A filter alone doesn't help if dust escapes around gaskets and seams. The Bissell MultiClean Allergen Lift-Off, Kenmore Intuition, and Shark Navigator Lift-Away NV356E all advertise sealed systems; high-trust testers note big real-world differences between sealed and unsealed designs.