Quoted:
If you're vaccinated you most likely won't get sick even if the whole fucking neighborhood is.
This isn't true for whooping cough (pertussis). It is mostly true for smallpox, measles, and tetanus (and many others). However, pertussis immunity is not only difficult to maintain (needs regular boosters), but effective immunity for pertussis is only 59-89% for individuals who are current on their vaccination. (Tetanus is 95%+ and smallpox immunity is almost 100%)
Pertussis is difficult to immunize for two reasons.
The first is that pertussis is really virulent. 50% of people who are not vaccinated will develop pertussis from a casual exposure. (It's 90% for those who have regular exposure.) Those numbers are similar to smallpox which is generally regarded as one of the most virulent diseases ever. Even with immunization, pertussis infection rates are still about 15% for those who have regular exposure.
The second reason is that pertussis does not stimulate a strong immune response even for those with vaccination or direct exposure. This is inherent in the disease. Our body's just don't see pertussis as the invasive threat that it is. This is why boosters are required and why even people who have been vaccinated still get sick. This is also why people can have whooping cough for months if not years.