I've been asking myself the same questions that you have but I haven't looked into it yet as I'm tied up with other research.

I'd be really interested for you to take this one step further and I'd love to see the results. For example:

Cairns - Great Barrier Reef

• Number of residents = 150,000
• % of residents vaccinated per the recommended schedule (it's a sliding scale with some 100% and others eg. 60%)
• Tourists arriving from each country into Cairns (not sure but the Great Barrier Reef attracts 2 million tourists per year - not sure if that also includes domestic)
• Vaccinations rates in the countries of the tourists visiting Cairns
• Reported cases of diseases in Cairns that vaccines are reported to protect against

On average 25% of Cairns population are tourists at any given time. I would think that the number would be higher during the non-monsoonal months but I have not checked. You might find that the percentage is much higher during certain months. Again, not sure if this number includes domestic tourists or not (that requires more research).

N.B: Going one step further again you could break it down into age groups and diseases. No need for that to begin with but if you're first findings can show that we are already below the herd immunity rate it might be worth delving deeper.

You may find that the numbers blow the herd immunity theory out of the window?

I know that this is a fair bit of work, but I think that it is important work. Someone else may have already done some research on to it that you can piggy-back off?

I would start with countries that have low vaccine rates and cross check them with the tourism numbers from those countries - you might find some quick wins there e.g. China, India etc.

I hope that you, or someone else can make time to look into this. The results will be very interesting to see.

Thank you for this post and well done!