Is it necessary to use a vacuum cleaner/hoover?

The secretion can not be removed from the nasal cavities, unless you have strong continuous suction.

Is the procedure sterile enough?

The Baby-Vac doesn't need to be sterile. It's enough to sterilize the evacuator (A) by putting it into boiling water occasionally. If you use it continually it's enough to wash the whole apparatus …

The device is tested by internationally recognized bodies