We've been increasing the priority of the smallpox task so you should see mostly if not all your work set as smallpox if you are available for all projects. If you are cancer only you will still get cancer work and if you only want to do cancer you can still switch your computer to cancer only if you like.
No its not that many people have opted out of smallpox. Less than 8% of active users have cancer only set in their device profiles. Looking at the daily results stats it is clear that we have switched project priority. The ratio is at approx 9:1 in favor of smallpox.