Hi EJ, basically no you guys are not all clear even though you've had the vaccination. It is not 100% effective and does not cover all strains of whooping cough. At the moment there is quite a lot of the strain not covered by the vac around so it may not have mattered that your mum didn't have her vac because it may be a different strain anyway.

Be sensible, get your mum to keep her distance until she knows for sure, which you really should do with kids/babies when you're not well anyway.

Hope she doesn't have WC and feels better soon
Couldn't have said it better myself. A couple of years back my two step sons both got whooping cough despite being "fully" vaccinated. One had a nasty lingering cough for 3-4 months. Evenmy vaccinated husband got a mild cough which was probably whooping cough. Myself and my son are not vaccinated for whooping cough, and neither of us caught it at all. When we questions the doctors as to why the vaccinated kids caught it, we were told the most common strain of whooping cough around at the moment is not covered at all by the vaccination, and therefore the vaccinated kids actually had no immunity to it. It's possible that at some stage I had this strain of whooping cough and developed immunity to it which I passed on to my son through my breastmilk...