In-transit passengers, irrespective of the time period in-transit, will still require proof of the vaccination.
The new ruling comes into effect immediately, but there will be a grace period, as far as we know until 1 July 2011 (subject to confirmation from the Department of Health).
You will be required to have the vaccination a minimum of 10 days before arrival, however the vaccination is valid for 10 years.
Zambia is the latest country to require Yellow Fever Vaccinations. Countries in East Africa (Kenya and Tanzania) have required the same vaccination for many years. Yellow fever is a viral infection transmitted by mosquitoes.
If you plan to travel to Zambia soon, contact your nearest travel clinic to arrange for the vaccination.