Trillian, I completely agree with your concerns about the "one size fits all" dosing of vaccinations. I agree that it is a potential problem that some vaccinations are used in the same strengths for a two year old as they are for a four year old - those of us who have had two and four year olds will appreciate the incredible difference in size and development between those years.

With regards to the pertussis (whooping cough) outbreak, we are right in the middle of it here on the mid north coast of NSW. There are a few factors that combine to make whooping cough the most common outbreak that we see of vaccine preventable disease. The pertussis vaccine is at best 90% effective, which means that even if you immunise every single person you will always have 10% of the population who are susceptible. Immunity from the vaccine wanes over time, so you will also always have a sizeable adult population who are not immune to it. And the contagious period begins before the classic "whooping cough" cough starts - in actual fact, whooping cough starts with nothing more sinister than cold and flu-like symptoms.

The good news is that you need a significant exposure to someone else with pertussis to catch the disease - something in the order of 2-4 hours of close contact. This is why it temnds to spread within families, but not so much among the general community.

Our paediatrician advised that given that we are expecting a new baby, we ourselves, and our two girls, should be immunised against it, which was quite surprising, given that he is reasonably anti-immunisation himself. We agonised over our decision, but in the end we decided not to. We are happy to be vigilant, and we have taught our girls a lot of basic hygiene, and they know that if they start to feel sick they have to tell us and that they can't then play, kiss, etc. the other person.

As far as being a carrier of whooping cough, there really isn't any such thing - if you catch it, you either develop symptoms or you don't, but even if you don't develop symptoms, you still only remain contagious for 2-3 weeks. After that you gain immunity for anything from 10-30 years. Same with the immunisation, unless you are in the 10% that doesn't respond.