Wash with 60c mostly can kill the dust mite.

But vacuum is not 100%. Flat surface and surface is ok for vacuum. But for those sewing seam area ( a line along which two pieces of fabric are sewn together) and inner layer will have difficult to vacuum penetrate.

And the bed wood joint or hole. Thick pillow, fabric sofa, All this have a hard time for the vacuum to suck deep.

So far I test with vacuum, chemical spray and steamer, only the steamer is the most effective. With the over 100c hot and penetrate deep into fabric, it 100% kill the dust mite.

For sofa, I change to leather. Which is easy to clean kill the dust mite compare fabric.

Not just the temperature. But the steam pressure.

Garment is a thin fabric. You don't need high pressure to push the steam out. So most of the garment steamer are not certified for dust mite. You can tell by the steam out from the nozzle. But don't use your hand. It can burn your skin.

Steamer certified dust mite require higher pressure and temperature to push the steam out further. So it can penetrate further in. Instead just the surface. Those steamer normally have a higher watt and pressure bar. 1200w - 1800w and pressure bar of 1.5 or 2(if not mistaken).

A good steamer usually won't have water droplet. I use before those cheapo handheld steamer from china. Water droplet no control. I throw it away.

I only steam it when change bed sheet. After steam, leave it there. Later at night only put on the bed sheet. For sofa cushion, you can steam it and immediately sit on it.  You can vacuum 1st and steam it later for better result. But I m lazy. So steam it is enough. I steam anything that suspect the dust mite hide. Wood, fabric, leather etc.

Steamer not just kill dust mite. It kill anything when go through the crazy hot steam nozzle. That is what I like better than vacuum.