https://duckduckgo.com/?ratb=c&q=autism+vaccine+link&t=h_&ia...
https://www.google.com/search?q=autism+vaccine+link
The 3rd result on duckduckgo.com is learntherisk.org. That result is not presented in the first 10 pages of results on Google.
It seems quite likely to me that one of these sites is manipulating search results. Because the organic search results for these two different search engines should not be that far apart.
Edit: Why the downvotes? Here is an even more egregious example:
Try searching for "learn the risk autism".
https://duckduckgo.com/?ratb=c&q=learn+the+risk+autism&t=h_&...
https://www.google.com/search?q=learn+the+risk+autism
Note that I am not promoting an agenda here. This seems like an example of manual manipulation. The article sites "vaccinations and autism" as an example.